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L.  B.  Cat.  No.  1 137 


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1T504 


Ube  IRitral  Science  Series 

Edited  by  L.  H.  BAILEY 


THE   POTATO 


Efte  iaural  Science  Scricg 

Edited  by  L.  H.  Bailey 

The  Soil.     King. 

The  Spraying  of  Plants.     Lodeman. 

Milk  AND  ITS  Products.    Wing.    Enlarged  and  Revised. 

The  Fertility  of  the  Land.     Boherts. 

The     Principles    of    Fruit-growing.     Bailey.     20th 

Edition,  Bevised. 
Bush-fruits.     Card.     Bevised. 
Fertilizers.     Voorhees.     Bevised. 
The  Principles  of  Agriculture.    Bailey.     Bevised. 
Irrigation  and  Drainage.     King. 
The  Farmstead.     Boherts. 
Rural  Wealth  and  Welfare.     Fairchild. 
The  Principles  of  Vegetable-gardening.   Bailey. 
Farm  Poultry.     Watson.    Enlarged  and  Bevised. 
The    Feeding    of   Animals.      Jordan.       (Now   Eviral 

Text-Book. ) 
The  Farmer's  Business  Handbook.     Boberts. 
The  Diseases  of  Animals.     Mayo. 
The  Horse.     Boberts. 
How  TO  Choose  a  Farm.     Hunt. 
Forage  Crops.     Voorhees. 

Bacteria  in  Relation  to  Country  Life.     Lipman. 
The  Nursery-book.     Bailey. 
Plant-breeding.     Bailey  and  Gilbert.     Bevised. 
The  Forcing-book.     Bailey. 

The  Pruning-book.   Bailey.   (Now  Rural  Manual  Series.) 
Fruit-growing  in  Arid  Regions.   Paddock  and  Whipple. 
Rural  Hygiene.     Ogden. 
Dry-farming.     Widtsoe. 
Law  for  the  American  Farmer.     Green. 
Farm  Boys  and  Girls.     McKeever. 
The  Training  and  Breaking  of  Horses.     Harper. 
Sheep-farming  in  North  America.     Craig. 
Cooperation  in  Agriculture.     Powell. 
The  Farm  Woodlot.     Cheyney  and  Wentling. 
Household  Insects.     Herrick. 
Citrus  Fruits.     Coit. 

Principles  of  Rural  Credits.     Morman. 
Beekeeping.     Phillips. 

Subtropical  Vecjetable-gardening.  Bolfs. 
Turf  for  Golf  Courses.  Piper  and  Oakley. 
The  Potato.      Gilbert. 


THE  POTATO 


BY 


ARTHUR   W.    GILBERT,   Ph.D. 

PROFESSOR    OF    PLANT-BREEDING,    NEW    YORK    STATE    COLLEGE 
OF    AGRICULTURE    AT    CORNELL    UNIVERSITY 


ASSISTED    BY 

MORTIEE  F.   BARRUS,   Ph.D. 

PROFESSOR    OF    PLANT    PATHOLOGY,    NEW    YORK    STATE    COLLEGE 
OF    AGRICULTURE    AT    CORNELL    UNIVERSITY 

AND 

DANIEL  DEAN 

FORMERLY    PRESIDENT    OF    THE    NEW    YORK    STATE 
POTATO   ASSOCIATION 


THE   MACMILLAN   COMPANY 
1917 

All  rights  reserved 


COPTBIGHT,    1917, 

By  the   MACMILLAN  COMPANY. 


Set  up  and  electrotyped.     Published  March,  1917. 
Reprinted  November,  1917. 


NorbjooU  ?3t£88 

J.  8.  Gushing  Co.  —  Berwick  &  Smith  Co. 

Norwood,  Mass.,  U.S.A. 


PREFACE 

This  book  is  intended  to  give  brief  and  practical 
suggestions  on  the  growing,  breeding  and  marketing 
of  potatoes.  It  is  written  especially  for  the  practical 
farmer  and  the  student  who  may  wish  concise  informa- 
tion on  the  potato  without  having  to  read  many  mis- 
cellaneous sources  of  information,  especially  experiment 
station  bulletins  which,  although  highly  valuable,  are 
likely  to  contain  much  detail. 

The  chapters  on  breeding  and  varieties  occupy  an 
unusually  large  proportion  of  the  book.  This  is  for  the 
reason  that  these  subjects  have  been  treated  in  potato 
literature  much  less  than  methods  of  culture,  and  the 
general  interest  in  them  has  called  for  this  extended 
discussion  to  meet  not  only  the  necessities  of  the  case 
but  also  the  public  demand. 

I  have  been  glad  to  place  in  the  hands  of  Doctor  Bar- 
rus  and  Mr.  Dean  the  chapters  on  Diseases  and  Field 
Methods  respectively.  These  men  have  had  broad  ex- 
perience in  their  lines  and  are  thoroughly  competent  to 
discuss  them. 

The  author  wishes,  also,  to  acknowledge  the  valuable 
aid  of  Professor  Herrick  in  reading  the  manuscript  on 
Potato  Insects,  and  Mr.  A.  C.  Eraser  and  Mr.  J.  J. 
Pollock  for  valuable  assistance. 

ARTHUR  W.   GILBERT. 

Ithaca,  New  York, 
January,  1917. 


A  y^cz.f\^A 


CONTENTS 


OHAPTBE  ^a«^o 

I.     Acreage,   Distribution,    Production   and   Valu- 
ation .....••••  1-13 
II.     History •  14-20 

III.  Classification  and  Botanical  Characteristics  .  21-46 

Description  of  the  Irish  potato  —  Classification 
of  varieties  —  Important  varieties  of  Iowa  and 
the  Central  West — Tabulation  of  varieties  — 
Synonyms  —  Description  of  typical  varieties. 

IV.  Potato  Breeding 47-86 

Ideals  for  the  potato  crop  —  Use  of  score  card 
—  Possibilities  of  improving  the  potato  —  Meth- 
ods of  improvement  —  Improvement  of  the  potato 
by  selection  —  Running  out  of  varieties  —  Ap- 
pearance of  bud  sports  —  Improvement  by  hy- 
bridization. 
V.  Climate,  Soils  and  Rotation  ....  86-112 
Factors  influencing  potato  culture  —  Heat  — 
"Water  requirements  —  Soil  texture  —  Available 
plant-food  —  Drainage  and  soil  air  —  Critical 
period  —  Type,  variety  and  strain  —  Diseases  — 
General  types  of  potato-growing  in  the  United 
States  —  Soils  —  Rotation  —  Hay  plants. 

VI.     Manures  and  Fertilizers 113-132 

Fertilizer  practices  —  Market  forms  of  fer- 
tilizers —  Nitrogen  —  Phosphorus  —  Potassium 
—  Calcium  —  Sulphur  —  Applying  fertiUzers  — 
Farm  manures. 

vii 


Contents 


CHAPTER  PAQES 

VII.     Planting 133-169 

Tillage  tools  —  Results  of  tillage  —  Planting  — 
Hill  and  drill  planting  —  Planting  tools  —  Hand 
planting  —  Seed  potatoes  —  Cutting  seed. 

VIII.     Care  of  the  Growing  Crop 160-169 

IX.  Potato  Insects  and  Their  Control  .  .  .  170-182 
The  Colorado  potato-beetle — Flea-beetle  — 
Blister-beetle  —  The  three-lined  leaf-beetle  — 
Tortoise-beetles  —  The  potato  plant-louse  — 
Leaf-hoppers  —  The  potato-stalk  weevil  —  The 
stalk-borer  —  White  grubs —  Wire- worms. 

X.     Diseases  of  the  Potato 183-205 

Classification  of  causes  of  disease  —  Early 
blight  —  Late  blight  —  Rhizoctoniose  —  Fusa- 
rium  wilt  —  Verticillium  wilt  —  Fusarium  dry 
rot  —  Silver  scurf  —  Potato  wart  —  Common 
scab  —  Black-leg  —  Bacteria  wilt  —  Powdery 
scab  —  Tip-burn  —  Arsenical  injury  —  Spindling 
sprout  —  Net-necrosis  —  Curly  dwarf  —  Mosaic 
leaf-roll  —  Constitutional  degeneracy  and  other 
weakened  conditions  of  plants. 

XL    Control  Measures  against  Diseases     .         .         .     206-225 
Control  of  curly-dwarf,  mosaic  and   leaf-roll 

—  Field  inspection  —  Seed  treatment  to  prevent 
disease  —  Disease  from  organisms  already  in  soil 

—  Treatment  for  potato  blight  —  Preparation  of 
bordeaux  mixture — Other  remedies  —  Disease- 
resistant  varieties  —  Summary. 

XIL     Harvesting  the  Potato 226-236 

Time  to  harvest  —  Methods  of  digging  —  Pick- 
ing and  sorting  —  Labor  and  cost  of  harvesting. 
XIII.     Markets,  Marketing  and  Storage  .         .     237-258 

Marketing  through  local  dealers  —  Marketing 
the  crop  —  Grading  —  Packages  —  Shipping  — 
Early  and  late  potatoes  —  Markets  —  Range  and 
prices. 


Contents  ix 

CHAPTER  PAGES 

XIV.     Uses  of  the  Potato 259-280 

Use  for  human  food  —  Quality  when  cooked  — 
Use  for  starch  —  Process  of  starch  manufacture 
—  Uses  of  potato  starch  —  Uses  for  industi-ial 
alcohol  —  The  manufacture  of  alcohol  from  pota- 
toes—  Use  as  stock  food  —  Alcohol  slops  or  resi- 
due —  Potato  pomace  —  Poultry  food  —  Dried 
or  desiccated  potatoes  —  Potato  flour. 

XV.     Cost  of  Growing  Potatoes 287-313 

Results  of  a  survey  in  New  York  state —  Other 
survey  results  —  Cost  of  hauling. 


LIST   OF   PLATES 


PLATE  PACING   PAGE 

I.     The  potato  as  first  grown  in  Europe        ...       19 

II.  Types  of  potato  tubers,  as  illustrated  by  the  Wis- 
consin Experiment  Station       ....       32 

III.  A  plate  of  smooth  potatoes  with  few  and  shallow 

eyes  —  the  breeder's  ideal        ....       48 
(Photo  by  Farm  Crops  Dept.,  Cornell  University) 

IV.  Illustration  of  good  shaped  potato  for  table  use. 

Variety,  Green  Mountain         ....       51 
(Photo  by  Farm  Crops  Dept.,  Cornell  University) 

V.  Typical  early  and  late  potatoes.  Top,  Irish  Cob- 
bler   (early).     Bottom,    Rural    New    Yorker 

(late) 53 

(Photo  by  Farm  Crops  Dept.,  Cornell  University) 

VI.  Breeding.  Each  group  of  four  plates  represents  the 
progeny  of  a  tuber,  and  each  plate  is  the  prod- 
uct of  a  single  hill    ......       56 

VII.  Tubers  with  histories.  Upper,  influence  of  growing 
season,  showing  the  second-growth  tubers  on 
the  right  compared  with  the  normal  uniform 
tubers  on  the  left.  Lower,  breeding.  —  The 
immunity  and  susceptibility  of  two  tuber 
progenies 61 

VIII.     Seed   potatoes.     Top,   different   ways  of  cutting. 

Bottom,  good  and  bad  types  for  seed      .         .     100 
xi 


xii  List  of  Plates 

PLATE  FACING   PAGE 

IX.     Potato  diseases.     Upper  tuber,  rot  caused  by  late 
blight ;  two  bottom  tubers,  net  necrosis.    Leaf, 
under  surface,  showing  effect  of  late  blight      .     190 
(Tuber    cuts  —  Courtesy    of    Dept.    of    Plant 
Pathology,     College     of     Agriculture,     Cornell 

University) 
(Leaf  cut  —  Courtesy  of  the  Geneva  Agricul- 
tural  Experiment   Station   Bulletin   241,   Plate 
XII) 

X.     Potato    diseases.       Top,   part    of    a    potato    leaf, 
showing     spots     of     early     blight.     Bottom, 

rhizoctoniose 194 

(Courtesy  Dept.  of  Plant  Pathology,  College  of 
Agriculture,  Cornell  University) 

XI.     Potato   diseases.       Left,   powdery   scab.       Right, 

fusarium  dry  rot 196 

(Courtesy  Dept.  of  Plant  Pathology,  College  of 
Agriculture,  Cornell  University) 

XII.     SpindUng  potato  sprouts.     Upper  picture,  rhizoc- 
toniose    ........     198 

(Courtesy  Dept.  of  Plant  Pathology,  College  of 
Agriculture,  Cornell  University) 

XIII.  Preparing  the  bordeaux  mixture     ....     217 
(Courtesy  Dept.  of  Plant  Pathology,  College  of 

Agriculture,  Cornell  University) 

XIV.  The  potato  harvest.     View  in  an  eastern  field        .     232 
XV.      Combined  potato  digger  and  loader        .         .         .     233 

(Photo  by  W.  C.  Blake) 
XVI.      Potato  products 259 


THE   POTATO 


THE    POTATO 


CHAPTER  I 

ACREAGE,  DISTRIBUTION,   PRODUCTION  AND 
VALUATION 

The  potato  is  one  of  the  most  widely  cultivated  of  the 
agricultural  plants.  The  esculent  tubers,  which  are  devel- 
oped underground  on  slender  leafless  shoots  or  stems,  are 
used  for  food  and  also  industrially.  The  plant  is  allied 
botanically  to  several  powerful  narcotics,  such  as  tobacco, 
henbane  and  belladonna,  and  also  to  the  tomato,  egg- 
plant and  capsicum. 

The  potato  comprises  about  25  per  cent  of  the  food 
of  European  and  English-speaking  peoples.  Only  the 
Oriental  peoples  exist  without  it.  A  greater  weight  of 
potatoes  can  be  produced  to  a  unit  area  than  any  other 
food  crop. 

The  yield  in  millions  of  tons  of  the  world's  most  im- 
portant plants  is  shown  in  the  following  table : 

Table  I.  —  World's  Crops  of  the  Most  Important  Food 
Plants,  in  Million  Tons.  Average  for  5  Years,  1908- 
1912 

Potatoes 161.0 

Corn 128.38 

Wheat        106.0 

Oats 65.6 

Ricei 55.6+ 

Rye 57.0 

Barley        33.41 

1  This  figure  does  aot  represent  the  rice  crop  of  the  world,  as  statistics 
fFom  certain  sections  of  China  are  lacking. 
B  1 


nOPERU  UBRARY 

N.  C.  State  CMtit 


2  Tlie  Potato 

The  average  annual  production  of  potatoes  in  the  world 
for  the  last  ten  years  has  been  over  5,000,000,000  bushels. 
The  production  of  wheat,  corn  and  oats  has  been  approxi- 
mately 4,000,000,000  bushels  each.  Potatoes,  therefore, 
lead  the  other  crops  in  total  production. 

This  immense  total  world  production  is  generally  and 
widely  distributed.  The  six  leading  countries  and  their 
average  annual  production  for  the  years  1911-1913,  and 
the  average  yields  an  acre  for  the  years  1904-1913,  are 
as  follows  (see  Fig.  1) : 

Table  II 


Total  Production 
IN  Bushels 


Average  Yield  an 
Acre  in  Bushels 


Germany      .     . 

European  Russia 

Austria-Hungary 

France 

United  States   . 

United  Kingdom 


1,698,826,000 
1,258,120,333 
642,149,000 
499,523,666 
348,303,000 
259,482,666 


200.7 
106.4 
134.35 
130.2 
96.5 
210.0 


About  90  per  cent  of  the  world's  crop  is  grown  in 
Europe,  Germany  and  Russia  producing  more  than  half  of 
the  total  crop.  The  United  States  produces  only  about 
one-fifth  as  much  as  Germany.  This  is  largely  due  to 
the  fact  that  the  German  consumption  per  capita  is  about 
two  and  one-half  times  as  great  as  ours,  and  that  more 
than  50  per  cent  of  the  German  crop  is  used  either  for 
stock  food  or  for  conversion  into  starch,  alcohol  or  other 
industrial  by-products.  Potatoes,  at  present,  are  used 
very  little  for  these  purposes  in  this  country,  less  than  1 
per  cent  being  so  employed. 


Acreage  and  Value 


Table  III.  —  Percentage  of  World's  Potato  Crop  ^  Pro- 
duced BY  THE  Continents,  and  Principal  Potato-pro- 
ducing Countries.     For  the  Years  1908-1912 


Continents 


Bushels 


Per  Cent 
World's  Crop 


Europe  .  .  . 
North  America 
Asia  .... 
South  America 
Australia  . 
Africa    .     .     . 


4,817,830,200 

425,239,800 

54,329,000 

38,931,000 

13,813,600 

4,793,200 


89.72 

7.92 

1.01 

.73 

.26 

.09 


Principal  Countries 

Total  Bushels 

1908-1912, 

Per  Cent 

World's  Crop 

Germany 

Russia 

Austria-Hungary 

France  

United  States 

1,624,801,000 

1,209,513,400 

664,538,200 

514,542,200 

346,119,200 

30.25 

22.52 

12.39 

9.58 

6.45 

The  cultivation  of  the  potato  is  now  extended  over  most 
of  the  agricultural  sections  of  the  Ignited  States  and 
Canada  and  it  is  becoming  increasingly  important  as  an 
article  of  human  food  in  this  country.  It  ranks  sixth  in 
agricultural  importance  in  the  United  States. 


Table   IV.  —  Relative  Value   op  Crops   in  the  United 
States  in  Dollars  (1908-1912) 

Corn 1,512,780,000 

Hay 768,330,000 

Cotton        724,710,000 

Wheat 666,940,000 

Oats 412,360,000 

Potatoes 209,720,000 

Barley 107,710,000 

Tobacco 94,429,000 

»  Average  of  world's  crop  for  1908-1912  =  5,369,590,000  bushela. 


The  Potato 


Acreage  and  Value  5 

The  following  table  illustrates  graphically  the  distribu- 
tion of  potato-growing  in  the  United  States  (see  Fig.  2). 

In  the  United  States,  New  York  has  led  in  potato  pro- 
duction for  the  last  twenty-five  years.  The  leading  states 
and  yield  to  the  acre  are  as  follows :  ^ 

Table  V 


State 

Production  in 

Millions  op 

Bushels, 

1911-1915 

Yield  to 
THE  Acre, 
1906-1915 

Average  Price 
A  Bushel, 
1906-1915 

New  York 

Michigan 

Wisconsin 

Minnesota 

Maine 

Pennsylvania      .... 

3.3.35 
33.27 
32.80 
30.04 
25.67 
23.13 

97 

94 

102 

102 

204 

85 

Cents 

63 
59 
87 
44 
54 
68 

In  the  last  few  years,  Michigan,  Wisconsin,  Maine  and 
Minnesota  have  been  rapidly  gaining  in  production,  and 
are  now  all  close  rivals  of  New  York. 

For  the  ten  years  1902-1911  inclusive,  an  average  of 
3,230,000  acres  was  devoted  to  the  potato  crop  in  the 
United  States,  from  which  304,158,000  bushels  were  pro- 
duced, w^orth  $177,503,000.  This  comprises  only  about 
one-sixth  of  the  w^orld's  crop. 

Ten  states  along  the  northern  border,  where  the  climate 
is  cooler  and  the  crop  is  supplied  with  more  moisture,  pro- 
duced nearly  two-thirds  of  the  potato  crop  of  the  United 
States  (see  Figs.  3  and  4).  Potatoes  are  grown,  however, 
in  more  or  less  quantity  in  every  state  of  the  Union. 

As  the  agriculture  in  the  United  States  becomes  more 

'  After  Montgomerj.'. 


The  Potato 


Acreage  and  Value  7 

stable  and  railroad  facilities  develop,  there  is  more  and 
more  of  a  tendency  for  farm  crops  to  be  intensively 
grown  in  certain  areas  where  soil,  climate  and  other  factors 
are  best  suited  to  them.  This  is  especially  true  of  a  crop 
like  corn  or  wheat  which  is  neither  perishable  nor  very 
bulky  and  can  be    easily    shipped.     This    is    becoming 


I  £<  3S 


Fig.  3.  Percentage  of  the  potato  crop  of  the  United  States  which  is 
produced  in  each  of  the  15  states  of  largest  production,   1902-1911. 

increasingly  true  of  potatoes  because  of  their  bulkiness 
and  partial  perishableness. 

Most  of  the  potatoes  raised  in  the  United  States  are 
still  grown  as  a  cash  crop  in  relatively  small  parcels  on 
many  farms.  There  is  a  tendency,  however,  toward  the 
development  of  potato-growing  centers  in  widely  sepa- 
rated sections  of  the  United  States.  By  a  careful  inspec- 
tion of  the  map  on  page  6  one  can  see  that  these  areas 
are  located  in  Aroostook  County,  Maine,  the  Norfolk  and 
Eastern  Shore  trucking  regions  of  Virginia  and  Maryland, 
the  Red  River  Valley  of  Minnesota  and  North  Dakota, 
the  Kaw  Valley  of  Kansas,  the  Greely  and  Carbondale 
districts  of  Colorado,  and  the  San  Joaquin  and  Sacramento 
valleys  of  California. 


The  Potato 


NFW  VORK 

■i" 

^^ 

■■" 

MICHIGAN 

^^_ 

^^g 

m 

WlSCON<;ilM 

^^_ 

I^B 

_ 

(■■ 

mg^ 

H^ 

MINNESOTA 

PENNSYLVANIA 

|^_ 

^^^ 

■ 

OHIO 

mg^ 

^^^ 

IOWA 

|BHK 

=3 

ILLINOIS 

■^ 

Ed 

COLORADO 

CALIFORNIA 

^^^ 

^J 

DtiniAMA 

^^m 

VIRGINIA 

■i^ 

■™ 

NEBRASKA 

n_ 

pga 

. 

^■B 

^H 

3 

MISSOURI 

!■■■ 

WASHINGTON 

^^ 

KANSAS 

^^ 

"ZD 

NORTH   DAKOTA 

«5" 

KENTUCKY 

5^ 

OREGON 

■■5P 

IDAHO 

^■i 

' 

VERMONT 

■■p 

WEST  VIRGINIA 

^" 

MARYLAND 

^ 

SOUTH  DAKOTA 
MONTANA 

^ 

^^B   1909 
1                1    1899 

MASSACHUSETTS 

5 

TENNESSEE 

CONNECTICUT 

!!b 

UTAH 

? 

NORTH   CAROLINA 

? 

NEW  HAMPSHIRE 

5 

TEXAS                          , 

5" 

ARKANSAS 

5 

OKLAHOMA 

!P 

LOUISIANA 

P 

ALABAMA 

f 

Fig.   4.     Production  of  potatoes  in  the  different  states,  1909  and  1899. 


Acreage  and  Value 


9 


The  following  tables  from  the  thirteenth  census  indi- 
cate the  total  number  of  farms  in  certain  states  where 
potatoes  were  grown,  the  total  yield  and  the  total  amount 
to  each  farm.  The  latter  figure  shows  that  the  total  pro- 
duction on  most  farms  is  in  excess  of  the  family  con- 
sumption : 

Table  VI 


Bushels 

Bushels 

Bushels 

State 

County 

TO   A 

Farm 

County 

to  a 
Farm 

County 

TO    A 

Farm 

Mass. 

Berkshire 

128.5 

Hampshire 

112.3 

Hampden 

119.9 

Vt. 

Bennington 

169.2 

Chittenden 

154.5 

Addison 

116.1 

N.  J. 

Salem 

636.8 

Monmouth 

643.8 

Gloucester 

389.1 

Del. 

Kent 

44.3 

New  Castle 

83.8 

Sussex 

101.4 

W.  Va. 

Jackson 

42.9 

Wood 

48.1 

Preston 

43.4 

s.  c. 

Beaufort 

39.9 

Charleston 

33.0 

Colleton 

29.4 

Ga. 

Chatham 

189.4 

Thomas 

9.7 

Union 

11.0 

Fla. 

St.  John 

183.4 

HiUsboro 

22.1 

Gadsden 

13.7 

111. 

Cook 

161.7 

Madison 

188.6 

St.  Clair 

260.9 

la. 

Blackhawk 

92.5 

Grundy 

489.8 

Scott 

358.5 

Mo. 

St.  Louis 

167.2 

Buchanan 

127.9 

Ray 

135.6 

Neb. 

Sioux 

134.5 

Douglass 

134.2 

Cherry 

68.6 

Ky. 

Jefferson 

386.5 

Pike 

25.0 

Campbell 

98.9 

Ala. 

Mobile 

109.7 

Jefferson 

20.9 

Dallas 

3.8 

Tex. 

Harris 

58.7 

Cherokee 

32.0 

Cass 

15.3 

Wash. 

Yakima 

365.5 

King 

203.4 

Pierce 

166.7 

Id. 

Ada 

89.6 

Bingham 

802.4 

Lincoln 

120.7 

Af/f//V£ 
/V//V/V. 

CAL/r 

I/. -5. 


23f  % 


S23 


2.0d7o 


Fig.  5.  Percentage  of  the  improved  farm  land  that  was  annually 
planted  to  potatoes  in  the  ten  leading  states  of  the  United  States, 
1902-1911. 


10 


The  Potato 
Table  VII 


Number 
OF  Farms 


Total  Yield 


Total 
Amount 
TO  A  Farm 


Yield 

TO   THE 

Acre 

FROM 

Year- 
book, 
1914 


Northern  States 


Massachusetts 
Vermont  .  . 
New  Jersey     . 


36,917 
32,709 
33,487 


2,946,178 
4,145,630 
8,057,424 


79.8 
126.7 
240.6 


125 

155 

90 


Southern  States 


Delaware    .     . 
West  Virginia 
South  Carolina 
Georgia .     .     . 
Florida  .     .     . 


10,836 

96,685 

176,434 

291,027 

50,016 


880,360 
4,077,066 
782,430 
886,430 
856,967 


81.2 

42.1 

4.4 

3.1 

17.1 


Northern  Central  States  East  of  the  Mississippi  River 

Ohio 

Illinois 

272,045 
251,872 

20,322,984 
12,166,091 

74.7 
48.3 

93 
91 

Northern  Central  States  West  of  the  Mississippi  River 

Iowa 

Missouri 

Nebraska 

217,044 
277,244 
129,678 

14,710,247 
7,796,410 
8,117,775 

67.7 
20.8 
62.5 

89 

85 
78 

Southern  Central  States 

Kentucky 

Alabama 

Texas 

259,185 
262,901 
417,770 

5,120,141 
1,128,564 
2,235,983 

19.7 

4.2 
5.3 

92 
80 
50 

Far  Western  States 

Montana 

Washington    .... 
Idaho     

26,214 
56,192 
30,807 

3,240,696 
7,667,171 
4,710,262 

123.6 
136.4 
152.8 

180 
170 
200 

Acreage  and  Value 


11 


It  is  not  easy  to  determine  the  amount  of  the  family  con- 
sumption of  potatoes.  It  varies  with  different  regions. 
In  a  survey  of  483  farm  families  quite  widely  scattered, 
Funk  found  the  average  quantities  and  values  of  Irish 
potatoes  consumed  annually  to  a  person  in  the  following 
table : 

Table  VIII 


State 

Irish  Potatoes 

Bushels 

Value 

North.  Carolina 

Georgia 

Texas 

1.8 
1.5 
2.7 

5.7 
7.6 
8.6 
5.6 
5.6 
8.0 
9.7 

$2.13 
2.32 
3.24 

4  40 

Iowa 

Wisconsin 

Ohio 

4.42 
4.31 
2  81 

Pennsylvania 

2.80 
4  17 

Vermont 

3  98 

Average 

5.7 

$3.45 

The  average,  it  will  be  seen,  was  5.7  bushels  to  a  person. 
In  the  same  survey  was  found  an  average  of  4.6  persons 
in  the  family,  making  a  total  of  26.22  bushels  of  potatoes 
consumed  to  a  family.  Warren  ^  gives  the  average  quan- 
tity of  potatoes  raised  on  the  farm  and  used  in  the  house 
on  106  farms  in  Livingston  County,  New  York,  in  1909 
as  50.3  bushels  and  the  average  amount  to  an  individual 
as  10.1  bushels.  This  is  much  higher  than  the  figures 
Funk  obtained  in  his  survey,  but  even  at  this  high  figure, 
it  is  clearly  seen  that  most  farmers  have  at  least  a  few 
bushels  of  potatoes  to  sell. 

1  Warren,  G.  F.     "Farm  Management,"  p.  24. 


12  The  Potato 

In  a  farm  management  survey  of  Chester  County, 
Pennsylvania,  by  Spillman  ^  it  was  found  that  the  propor- 
tion of  income  from  potatoes  on  378  farms  in  that  county 
was  8.9  per  cent.  On  these  farms,  6  per  cent  of  the 
crop  area  was  devoted  to  potatoes.  "They  were  found 
on  366  of  the  378  farms  operated  by  owners.  This  crop 
is,  therefore,  very  general  in  this  region,  though  the  acre- 
age of  potatoes  is  usually  small.  On  only  seven  farms  was 
the  percentage  of  potato  acreage  found  to  exceed  20  (or  12 
acres)."  The  farmers  of  this  region  grow  at  least  enough 
for  home  use  and  usually  some  for  sale. 

The  yields  to  the  acre  are  dependent  upon  many  fac- 
tors, the  most  important  of  which  seem  to  be  climate 
and  soil  moisture.  Yields  to  the  acre  in  the  United 
States  are  low  as  compared  with  England  or  Germany. 
The  average  yields  of  potatoes  to  the  acre  for  the  years 
1901-1910  inclusive  in  the  United  States,  Germany  and 
Great  Britain  were  92.7,  200.8  and  200  respectively. 
European  countries  often  grow  the  large,  coarse,  heavy- 
yielding  sorts  for  stock-feeding  or  for  use  in  the  arts,  which 
accounts  for  some  of  the  difference  in  average  yields. 

In  the  United  States,  the  average  yield  to  the  acre  is 
higher  in  Maine  than  in  any,  other  state.  The  average 
yield  in  the  other  states  is  usually  90  bushels  or  less. 

Very  large  yields  in  the  United  States,  however,  are 
not  unheard  of.  A  yield  of  700  bushels  to  the  acre  in 
Maine  and  the  other  potato-producing  areas  is  not  un- 
common in  very  favorable  seasons.  Macoun,  in  speak- 
ing of  the  possibilities  of  the  potato,  makes  note  of  the 
highest  recorded  yield  of  potatoes  in  this  country.  These 
were  grown  by  Mrs.  Selinda  E.  Jones  of  Chautauqua 

1  Spillman,  Dixon  and  Billings.  "Farm  Management  Practice  of 
Chester  Co.,  Pa.,"  p.  26. 


Acreage  and  Value  13 

County,  New  York,  in  the  Women's  National  Potato 
Contest  of  1888.  She  grew  the  White  Elephant  variety 
on  one-twentieth  of  an  acre  at  the  rate  of  1061  bushels  to 
the  acre. 

In  the  United  States  the  average  yield  of  potatoes  from 
one  plant  is  about  one-half  pound.  Some  plants  of 
Early  Ohio  have  been  known  to  yield  thirteen  tubers 
weighing  2|  pounds,  and  others  of  the  same  variety  to 
produce  three  tubers  weighing  ^  an  ounce.  The  former 
yield  is  80  times  the  latter.  Some  English  experiments 
have  produced  twenty  pounds  of  tubers  to  a  plant,  as 
many  as  150  tubers  being  set  on  one  plant. 

The  climate  of  Canada  is  well  suited  to  the  produc- 
tion of  potatoes.  The  cool  summers  produce  a  yield  to 
the  acre  that  compares  very  favorably  with  the  best 
regions  of  the  United  States.  The  average  number  of 
acres  devoted  to  this  crop  for  the  years  1910-13  was 
476,000,  upon  which  an  average  yield  of  152.46  bushels 
to  the  acre  was  secured,  making  an  average  total  yield 
for  the  four  years  of  72,569,000  bushels. 

In  the  five  fiscal  years  1910-14,  Canada  exported  an 
average  of  1,451,990  bushels  of  potatoes  each  year,  of 
which  376,406  bushels  were  sent  to  the  United  States. 


CHAPTER  II 
HISTORY 

The  early  history  of  the  potato  is  a  matter  of  some 
doubt  among  historians,  but  all  are  agreed  that  it  came 
originally  from  the  high  lands  of  Peru  and  Chile,  where  it 
is  still  found  growing  wild. 

The  Spaniards  first  discovered  the  potato  in  the  neigh- 
borhood of  Quito,  Ecuador,  where  it  was  cultivated  by  the 
natives.  According  to  Pedro  Cie^a  de  Leon,  who  seems 
to  have  made  first  written  mention  of  the  potato  in  his 
"Spanish  Chronicles  of  Peru"  (1550),  the  inhabitants 
subsisted  largely  on  maize  and  what  they  called  "papas" 
and  "quinua."  The  former  is  the  Indian  name  for 
potato  and  the  latter  "is  a  plant  about  the  height  of  a 
man  and  has  leaves  like  the  blite  of  Mauritania,  and  a 
small  seed  either  red  or  white  in  color,  from  which  is 
prepared  a  drink,  and  a  food  comparable  to  our  rice." 

Potatoes  were  used  by  the  aborigines  in  place  of  bread, 
and  were  also  dried  in  the  sun  to  preserve  them.  They 
were  usually  cooked,  but  often  made  into  flour.  There 
was  evidence  of  long-continued  practice  of  cultivation, 
however  crude.  The  potato,  however,  was  and  still  is 
wild  in  the  mountainous  regions  of  Chile  and  Peru. 

The  potato  was  probably  carried  to  Spain  by  explorers 
in  the  sixteenth  century.  There  is  no  definite  record  of 
this  first  importation,  but  Rose  believes  that  it  jvas  as 
14 


History  15 

early  as  1533  or  1535,  at  the  time  of  the  conquest  of  Peru 
by  the  Spaniards,  Hieronymus  Cardan,  a  monk,  is 
supposed  to  have  been  the  first  to  introduce  it  from 
Peru  into  Spain,  and  from  thence  it  passed  quickly  into 
Italy,  Austria,  Germany,  Switzerland,  Belgium  and 
France.  The  first  figures  and  detailed  description  of  it 
in  its  new  home  in  continental  Europe  are  those  of  Clusius 
in  1601  in  his  "  Rariorum  Plantarum  Historia,"  although 
Bauhin  in  his  "  Phytopinax,"  printed  in  Basel  in  1596, 
described  it  and  gave  it  the  Latin  name  or  characteriza- 
tion, Solanum  tuberosum  esculentum.      (See  Plate  I.) 

The  date  and  method  of  introduction  of  the  potato 
into  North  America  are  not  definitely  known,  but  it  was 
probably  introduced  by  Spanish  voyagers  and  at  some- 
time before  1585,  for  it  is  clearly  recorded  that  its  first 
introduction  was  made  into  England  by  colonists  from 
Virginia  in  1586  under  the  patronage  of  Sir  Walter 
Raleigh. 

"It  seems  to  me  most  likely,"  says  De  CandoUe,  "that 
some  inhabitants  of  Virginia  —  perhaps  English  colo- 
nists—  received  tubers  from  Spanish  or  other  travelers, 
traders  or  adventurers,  during  the  ninety  years  which 
had  elapsed  since  the  discovery  of  America.  Evidently, 
dating  from  the  conquest  of  Peru  and  Chile,  in  1535  to 
1585,  many  vessels  could  have  carried  tubers  of  the  potato 
as  provisions,  and  Sir  Walter  Raleigh,  making  war  on 
the  Spaniards  as  a  privateer,  may  have  pillaged  some 
vessel  which  contained  them.  This  is  the  less  improbable,, 
since  the  Spaniards  had  introduced  the  plant  into  Europe 
before  1585." 

At  the  discovery  of  America,  we  are  told  by  Humboldt, 
the  plant  was  cultivated  in  parts  of  western  South 
America  from  Chile  to  Colombia  but  not  in  Mexico,  and 


16  The  Potato 

there  is  no  account  of  its  being  found  wild  in  other  parts 
of  North  America. 

From  1585  or  1586,  potato  tubers  were  brought  from 
what  is  now  North  Carohna  to  Ireland  on  the  return  of 
the  colonists  sent  out  by  Sir  Walter  Raleigh,  and  were 
first  cultivated  on  Sir  Walter's  estate  near  Cork.  This 
was  some  years  later  than  their  introduction  into  conti- 
nental Europe. 

In  1629,  Parkinson  in  his  "  Paradisus,"  in  which  he  gives 
an  indifferent  figure  of  the  potato  under  the  name  of 
Papas  seu  Battatas  Virginianorum,  adds  details  as  to  the 
method  of  cooking  the  tubers  which  seems  to  indicate 
that  they  were  still  luxuries. 

The  cultivation  of  the  potato  in  England  made  little 
progress  for  many  years.  It  is  said  that  in  the  time  of 
James  the  First,  they  were  so  rare  as  to  cost  two  shillings 
a  pound,  and  are  mentioned  in  1619  among  the  articles 
provided  for  the  royal  household.  In  1633,  when  their 
valuable  properties  had  become  more  generally  known, 
they  were  deemed  worthy  of  notice  by  the  Royal  Society, 
which  took  measures  to  encourage  their  cultivation  and 
for  introduction  into  Ireland,  especially  as  a  safeguard 
against  famine,  but  their  cultivation  has  become  general 
only  within  the  last  one  hundred  years. 

John  Gerard  received  some  tubers  of  the  potato  from 
Virginia  and  planted  them  in  his  garden.  He  gave  a 
careful  description  of  them  in  his  "Herbal,"  the  first 
edition  of  which  was  published  in  London  in  1597.  In  a 
later  edition  (1636)  he  pictures  them  by  means  of  a  wood- 
cut (see  Fig.  6).  He  was  so  proud  of  these  plants  that 
he  was  represented  in  his  portrait  at  the  beginning  of 
the  work  holding  a  flowering  branch  of  the  plant  in  his 
hand. 


History 


17 


It  should  be  noticed  how  closely  the  description  of  the 
potato  at  this  early  date  corresponds  with  the  plant  as 
grown  to-day.  He  says :  "  Virginia  potato  hath  many 
hollow,  flexible  branches  trailing  upon  the  ground; 
these  are  square, 
uneven,  knotted  or 
kneed  in  sundry 
places  at  certaine 
distances :  from 
the  which  knots 
Cometh  forth  one 
great  leafe  made  of 
divers  leaves,  some 
smaller  and  other 
greater,  set  to- 
gether upon  a  fat 
middle  rib  by 
couples,  of  a  swart 
green  colour  tend- 
ing to  redness ;  the 
whole  leaf  resem- 
bling those  of  the 
Winter-Cresses,  but 
much  larger ;  in 
taste  at  the  first 
like  grasse,  but  af- 
terwards sharp  and 
nipping  the  tongue. 
From  the  bosome  of  which  leaves  come  forth  long  round 
slender  foot  stalkes,  whereon  grew  very  faire  and  pleasant 
floures,  made  of  one  entire  whole  leafe,  which  is  folded  or 
plaited  in  such  strange  sort,  that  it  seems  to  be  a  floure 
made  of  five  sundry  small  leaves,  which  cannot  easily  be 


Copy  of  the  engraving  of  the  Vir- 
ginian potato  in  Gerard's  "Herbal"  —  printed 
in  1636. 


18  The  Potato 

perceived,  except  the  same  be  pulled  open.  The  whole 
floure  is  of  a  light  purple  colour,  striped  downe  the  middle 
of  every  fold  or  welt  with  a  light  show  of  yellownesse,  as 
if  purple  and  yellow  were  mixed  together.  In  the  middle 
of  the  floure  thrusteth  forth  a  thicke  flat  point  all  yellow 
as  gold,  with  a  small  sharpe  greene  pricke  or  point  in 
the  midst  thereof.  The  fruit  succeeds  the  floures,  round 
as  a  ball,  of  the  bigness  of  a  little  Bullesse  or  wild  plumme, 
green  at  first,  and  blacke  when  it  is  ripe,  wherein  is  con- 
tamed  small  white  seed  lesser  than  those  of  mustard ; 
the  root  is  thick,  fat,  and  tuberous,  not  much  differing 
either  in  shape,  colour  or  taste  from  the  common  potatoes, 
saving  that  the  roots  hereof  are  not  so  great  nor  long; 
some  of  them  are  as  round  as  a  ball,  some  oval  or  egge- 
fashion,  some  longer  and  others  shorter;  the  knobby 
roots  are  fastened  unto  the  stalkes  with  an  infinite  num- 
ber of  threddy  strings.  It  groweth  naturally  in  Americus 
where  it  was  first  discovered,  as  reporteth  Clusia,  since 
which  time  I  have  received  roots  hereof  from  Virginia, 
otherwise  called  Norembega,  which  grow  and  prosper  in 
my  garden  as  in  their  own  native  country.  The  leaves 
thrust  forth  on  the  ground  in  the  beginning  of  May ;  the 
floures  bud  forth  in  August,  the  fruit  is  ripe  in  Septem- 
ber. The  Indians  call  this  plant  pappas,  meaning  roots, 
by  which  name  also  the  common  potatoes  are  called  in 
those  Indian  countries.  We  have  its  proper  name  men- 
tioned in  the  title  'Potatoes  of  Virginia.'  Because  it 
hath  not  only  the  shape  and  proportion  of  potatoes  but 
also  the  pleasant  taste  and  vertues  of  the  same,  we  may 
call  it  in  English,  Potatoes  of  America  or  Virginia." 

In  1769,  the  grain  crops  of  France  were  a  failure,  threat- 
ening a  national  famine.  Parmentier,  a  Parisian  chemist, 
recommended  the  use  of  potatoes  as  food  to  take  the 


History  19 

place  of  the  grain  crops.  He  had  been  a  member  of  the 
medical  staff  of  the  French  army  in  1758,  during  the  war 
in  Hanover,  and  had  been  taken  prisoner.  During  his 
five  years  in  prison  his  principal  food  consisted  of  potatoes, 
which  were  then  grown  almost  exclusively  as  food  for 
animals.  The  dire  need  of  food  in  France  inspired  him 
to  write  a  book  called  a  "Treatise  on  Certain  Vegetables 
that  in  Times  of  Necessity  can  be  substituted  for  Ordinary 
Food."  This  book  was  received  with  ridicule  even 
though  it  received  a  certain  amount  of  support  from  the 
Paris  Agricultural  Society.  By  persistent  efforts,  Par- 
mentier  was  granted  a  small  patch  of  land  on  which  to 
experiment  with  his  potatoes.  The  king  ordered  the 
plot  to  be  guarded  by  a  cordon  of  troops  which  excited 
the  curiosity  of  the  people.  On  August  24th,  the  king's 
fete-day,  he  presented  the  king  with  a  basket  of  tubers 
and  a  bouquet  of  the  blossoms.  These  were  worn  by  the 
king  and  queen,  who  also  ate  the  cooked  tubers.  They 
were  found  to  be  very  palatable  and  soon  became  one  of 
the  foods  of  the  French  people. 

During  the  seventeenth  century,  the  potato  gradually 
became,  from  a  botanical  curiosity  cultivated  only  by 
collectors  of  new  plants,  one  of  the  staple  garden  and  field 
crops.  Its  cultivation  as  a  field  crop  became  somewhat 
common  in  Germany  soon  after  1772,  when  the  grain 
crops  failed  and  potatoes  were  used  as  a  substitute.  The 
quality  was  very  poor,  however,  and  even  though  they 
were  enormously  productive,  their  use  was  restricted 
largely  as  food  for  domestic  animals  and  they  were  used  as 
human  food  only  when  necessary  as  a  substitute.  By 
the  latter  half  of  the  eighteenth  century,  it  was  exten- 
sively cultivated  and  recognized  as  one  of  the  regular 
crops  throughout  the  temperate  regions  of  Europe  and 


20  The  Potato 

America,  so  that  Henry  Phillips  (1822),  who  published  a 
detailed  account  of  the  potato  and  its  culture,  was  able 
to  cite  a  single  grower  who  planted  300  acres  annually. 

In  Ireland,  they  were  used  very  extensively  as  human 
food.  By  1840  they  had  largely  replaced  the  cereals  and 
similar  food  crops  because  their  yield  in  weight  exceeded 
by  twenty  to  thirty  times  the  yield  of  wheat,  barley  or 
oats  on  an  equal  amount  of  land.  Dependence  upon  a 
single  crop  for  food,  however,  became  disastrous  for  the 
Irish.  The  potato  blight  which  appeared  in  the  United 
States  in  1845  devastated  Ireland  in  1846  and  caused 
a  widespread  famine.  It  is  conservatively  estimated 
that  600,000  persons  died  during  the  two  years  1846  and 
1847  for  want  of  food  or  from  diseases  caused  by  a  meager 
diet  of  unhealthy  and  unnutritious  food.  By  1848  the 
plague  had  practically  ceased. 

REFERENCES 

Campbell,  W.  H.  W.     The  Father  of  the  Potato.     Cosmopolitan, 

Vol.  II,  pp.  191-192.     1SS6. 
De  Candolle,  Alphonse.     Origin  of  Cultivated  Plants.     1-468, 

N.  Y.,  1892. 
Del'Ecluse  (ofClusius).  RariorumPlantarumHistoriae,  1601, lib. 
Gerard.     Herbal.     1597,  p.  781,  with  illustration. 
Meckel,  E.     The  Origin  of  the  Cultivated  Varieties  of  the  Potato. 

Rev.  Sci.  (Paris),  60:  1912,  II,  No.  21,  pp.  641-646. 
Henslow,  Geo.     The  Origin  and  History  of  Our  Garden  Vegetables 

and  Their  Dietetic  Values.     II.    Roots  +  tubers  (cont.). 

Roy.   Hort.  Soc.  Journ.,  36:   pp.  345-346,  Figs.    120- 

121  (1910-1911). 
Rose,  Ernest.     Histoire  de  la  pomme  de  terre  traitee  aux  points  de 

vue  historique,  cultural  ct  utilitaire.     1-464  Par.  1898. 
Sabine,  J.     On  the  Native  Country  of  the  Wild  Potatoes.     Trans. 

Hort.  Soc.  London,  Vol.  V,  pp.  249-259.     1824. 


CHAPTER  III 

CLASSIFICATION   AND    BOTANICAL    CHARAC- 
TERISTICS 

The  common  or  Irish  potato  is  known  botanically  as 
Solarium  tuberosum.  This  name  was  first  appHed  to  it 
by  Bauhin  in  his  "Phytopinax"  in  1596  (page  15)  and 
later  adopted  by  Linnaeus.  In  the  same  family  (Solana- 
cese)  are  many  other  plants  of  economic  importance,  as 
tomato,  eggplant,  tobacco,  belladonna,  henbane  and  cap- 
sicum or  red-pepper. 

Baker  has  reviewed  the  tuber-bearing  species  of  Solanum 
from  a  systematic  point  of  view  as  well  as  that  of  geo- 
graphic distribution.  Out  of  twenty  so-called  species  he 
considers  six  to  be  really  distinct,  while  the  others  are 
synonymous  or  trifling  variations.  The  six  admitted 
tuber-bearing  species  are  S.  tuberosum,  S.  Maglia,  S.  Com- 
mersonii,  S.  CardiophyUum,  S.  Jamesii  and  S.  oxycar- 
pum.     See  also  "Standard  Cyclo.  Hort."  VI,  3181. 

The  following  descriptions  of  species  have  been  taken 
from  Baker's  "A  Review  of  Tuber-bearing  Species  of 
Solanum" — Linnsean  Soc.  Journ.  Bot.,  XX:  pp.  489- 
507,  pis. 

Solanum  tuberosum,  Linn.  — vStems  stout,  erect,  much  branched, 
1-2  feet  long,  slightly  hairy,  distinctly  winged  on  the  angles.  Leaves 
1-2  feet  long,  slightly  hairy,  with  7-9  finely  pilose  oblong  acute  leaf- 
lets, the  side  ones  stalked  and  unequally  cordate  at  the  base,  the  1-2 
lowest  pairs  much  dwarfed,  petiole  about  1  inch  long.  Numerous 
small  leaflets  between  larger  ones.  Flowers  in  compound  terminal 
cymes  with  long  peduncles.  Corolla  wheel  shaped,  dark  lilac, 
21 


22  The  Potato 

nearly  1  inch  in  diameter.  Calyx  hairy,  \-^  inch  long,  with  teeth 
as  long  as  or  a  little  longer  than  the  campanulate  tube.  Berry 
globose,  less  than  an  inch  in  diameter,  smooth.  Native  of  Chile 
and  Ecuador. 

Solatium  Maglia,  Schlecht.  —  Stems  stout,  erect,  much  branched, 
1-2  feet  long,  strongly  winged  on  angles,  slightly  hairy.  Leaves 
6-9  inches  long,  larger  leaflets  5-7,  ovate  acute,  2-3  inches  long,  side 
ones  stalked,  unequally  cordate  at  base.  Flowers  in  compound 
cymes;  pedicles  downy.  Corolla  white,  subrotate,  f  to  1  inch  in 
diameter.     Style  twice  as  long  as  the  stamens.     Fruit  not  seen. 

Solanum  Commersonii,  Dunal.  —  Stems  shorter  and  more  slender 
than  in  S.  tuberosum.  Leaves  5-6  inches  long,  with  a  naked  petiole 
1-1 1  inches  long;  5-9  oblong  acute  leaflets,  the  terminal  one  much 
the  longest;  the  rachis  entirely  without  any  of  the  small  leaflets 
interspersed  among  the  large  ones.  Flowers  in  lax  compound  cymes. 
Calyx  ^-j  inch  long.  Corolla  pale  lilac  or  white.  Anthers  orange- 
yellow.  Style  distinctly  exserted  beyond  the  anthers.  South 
America. 

Solanum  cardiophyllum,  Lindley.  —  Of  the  same  general  habit  as 
S.  tuberosum.  No  small  leaflets  interspersed  amongst  the  large 
ones.  Whole  plant  quite  glabrous.  Foliage  very  dark  green. 
Leaflets  5,  large,  ovate  acute.  Flowers  in  compound  cymes.  Calyx 
glabrous.  Style  scarcely  longer  than  the  stamens.  Mountains  of 
Central  Mexico  at  an  elevation  of  8000-9000  feet. 

Solanum  Jamesii,  Torrey.  —  Minute  globose  tubers.  Leaves  dis- 
tinctly petiolate,  with  .5-9  oblong  acute  leaflets ;  no  smaller  leaflets 
interspersed  amongst  the  longer  ones.  Cymes  few  flowered.  Co- 
rolla white.  Fruit  globose.  Mountains  of  southwestern  United 
States  and  Mexico. 

Solanum  oxycarpum,  Schiede.  —  Tubers  minute.  Leaflets  5-9, 
oblong  lanceolate,  with  no  smaller  leaflets  interspersed  amongst  the 
larger  ones.     Cymes  few  flowered.     Fruit  ellipsoidal. 

DESCRIPTION   OF  THE   IRISH   POTATO 

The  common  potato  owes  its  value  to  the  peculiar 
habit  of  developing  underground  slender  leafless  shoots 
or  branches  which  differ  in  character  and  office  from 
the  true  roots,  and   gradually  swelling  at  the  free  end 


Description  and  Classification  23 

produce  the  tubers  (potatoes),  which  are  the  common 
vegetable  food.  The  nature  of  these  tubers  is  further 
rendered  evident  by  the  presence  of  "eyes"  or  leaf- 
buds,  which  in  due  time  lengthen  into  shoots  and  form 
the  haulm  or  stems  of  the  plant.  Such  buds  are  not, 
under  ordinary  circumstances,  formed  on  roots.  This 
budding  of  the  tubers  furnishes  an  efficient  method 
of  propagation,  independent  of  seed  production.  Starch 
and  other  matters  are  stored  up  in  the  tubers,  as  in  the 
seed,  and  are  rendered  available  for  the  nutrition  of  the 
young  shoots.  When  grown  under  natural  circumstances, 
the  tubers  are  relatively  small,  and  close  to  the  surface 
of  the  soil,  or  even  lie  upon  it.  In  the  latter  case,  they 
become  green  and  have  an  acrid  taste,  which  renders  them 
unpalatable  to  human  beings,  and  as  poisonous  qualities 
are  produced  similar  to  those  of  many  Solanacese,  they 
are  unwholesome.  Hence  the  recommendation  to  keep 
the  tubers  in  cellars  or  pits  not  exposed  to  the  light. 
Among  the  900  species  of  Solanum,  less  than  a  dozen 
have  this  property  of  forming  tubers.  The  production 
of  small  green  tubers  on  the  haulm,  in  the  axils  of  the 
leaves  of  the  potato,  is  not  very  infrequent,  and  affords 
an  interesting  proof  of  the  true  morphological  nature  of 
the  underground  shoots  and  tubers.  This  phenomenon 
follows  injury  to  the  phloem  in  the  lower  parts  of  the 
stem,  preventing  the  downward  flow  of  the  elaborated 
sap. 

CLASSIFICATION   OF  VARIETIES.       PLATE    II 

For  the  sake  of  convenience,  the  many  varieties  which 
are  now  on  the  market  may  be  classified.  No  one  classi- 
fication, however,  will  be  adequate  to  cover  all  conditions. 
Varieties  differ  somewhat  from  one  part  of  the  country 


24  The  Potato 

to  another.  Most  standard  varieties  have  many  syn- 
onyms which  make  the  whole  matter  more  confusing. 
The  frequent  appearance  of  new  names  for  old  varieties 
is  as  much  the  fault  of  the  grower  as  it  is  of  the  seedsman. 
There  is  a  strong  demand  for  new  things.  The  seeds- 
man attempts  to  meet  this,  but  most  of  our  seedsmen 
are  professedly  not  originators  of  new  varieties,  and  the 
supply  of  strictly  new  varieties  must,  of  necessity,  be 
very  limited,  hence  the  demand  is  met  by  changing  the 
name  of  some  old  variety  and  giving  extensive  advertis- 
ing under  its  new  name.  The  gullible  grower  accepts 
the  dose,  pays  the  price  for  the  supposedly  new  article 
and  is  satisfied  until  he  learns  that  it  is  nothing  new  and 
then  he  turns  around  and  repeats  the  process  again. 

The  number  of  named  varieties  is  so  large  that  the 
chances  of  finding  something  far  superior  are  very  slight. 
However,  it  is  not  at  all  impossible  to  find  such  a  variety  if 
one  has  the  patience  to  look  for  it  or  the  skill  to  produce  it. 
However,  for  the  average  grower,  it  is  much  better  to  stick 
to  the  old  standard  sorts  which  are  recognized  in  the  mar- 
ket. If  better  varieties  are  demanded,  it  is  wiser,  in  gen- 
eral, to  start  with  standard  varieties  which  have  already 
reached  some  degree  of  perfection  and  improve  them. 

The  potato  is  very  susceptible  to  differences  in  soil 
and  climate,  and  varieties  often  lose  their  distinguishing 
characteristics  when  grown  under  what  might  be  con- 
sidered unusual  environment.  There  has  also  grown  up, 
of  course,  a  wide  range  of  opinion  as  to  what  the  standards 
of  certain  varieties  are.  The  standard  of  a  variety  in 
one  locality  may  be  very  different  from  the  accepted 
standard  of  that  same  variety  in  another  locality.  The 
introduction  of  new  varieties  which  may  be  but  slight 
variations  from  the  old  sorts  has  still  further  complicated 

nOrERTY  LlBRARt 
mf  r   Qf^*M  fnllfite 


Description  and  Classification  25 

the  situation.  Moreover,  many  so-called  new  varieties 
are  merely  the  old  varieties  under  a  new  name.  But  on 
the  whole,  the  old  standard  varieties  may  be  recognized 
fairly  accurately. 

Potatoes  may  be  classified  according  to  the  shape  of 
the  tubers.  "Tubers  are  not  always  of  the  same  form; 
three  moderately  distinct  and  fairly  constant  types  are 
prevalent,  namely,  (1)  round,  (2)  oval  and  (3)  kidney 
shapes.  The  round  type  is  somewhat  spherical  and  has 
fewer  internodes  and  'eyes'  than  the  oval  or  kidney- 
shaped  potatoes.  The  kidney  potatoes  are  thickest  at 
the  stem  or  basal  end  and  taper  gradually  at  the  apex 
or  seed  end,  while  the  oval  varieties  are  thickest  in  the 
middle  and  taper  towards  both  ends  (see  Fig.  7).  These 
differences  are  sufficiently  marked  and  constant  for  a 
comparison  of  the  varieties  in  cultivation."  —  Percival. 

Important  varieties  of  Iowa  and  the  Central  West 

C.  L.  Fitch,^  of  the  Iowa  State  College,  made  a  thor- 
ough trial  for  a  series  of  years  of  all  varieties  of  commercial 
importance  in  the  United  States  and  Europe.  He  made 
also  a  canvass  in  person  and  by  letter  of  the  markets 
of  the  United  States.  The  result  was  that  only  a  few 
varieties  were  found  to  be  of  much  commercial  impor- 
tance. He  lists  the  following  varieties  as  being  the  most 
valuable  in  the  United  States  in  order  of  their  importance  : 

1.  Rural  5.  Irish  Cobbler 

2.  Green  Mountain  6.  Bliss  Triumph 

3.  Early  Ohio  7.  Peerless  (Pearl) 

4.  Burbank 

1  Fitch,  C.  L.  "Identification  of  Potato  "Varieties."  Iowa  Extension 
Bui.  20  (1914). 


26 


Tlie  Potato 


Description  and  Classification  27 

Fitch  says  that  the  varieties  Rural,  Early  Ohio  and 
Irish  Cobbler  are  the  outstanding  varieties  of  Iowa.  In 
regard  to  the  others,  he  makes  the  following  comments : 

"The  following  are  grown  in  Iowa  to  a  greater  or  less 
degree  or  reach  our  markets. 

"  Green  Mountain,  the  second  most  important  variety 
in  the  United  States,  and  a  second  best  late  sort  for  Iowa. 

"  Burbank,  still  the  standard  of  the  U.  S.  Government 
for  market  quotations,  formerly  important  in  Iowa,  and 
at  some  seasons  still  important  in  the  supply  of  her  cities. 

"  Peerless  or  Pearl,  by  test  at  Ames,  ranking  among  the 
best  late  sorts,  and  often  coming  into  her  markets  from 
Colorado  or  Wisconsin. 

"  Bliss  Triumph,  sometimes  grown  in  Iowa  for  very  early 
use,  and  extensively  grown  in  the  South  for  the  supply 
of  the  early  markets  of  Iowa  and  the  northern  states." 

William  Stuart  of  the  United  States  Department  of 
Agriculture  has  recently  made  a  very  comprehensive  and 
admirably  arranged  classification  of  potatoes.  His  bulle- 
tin contains  not  only  a  valuable  key,  but  a  careful  descrip- 
tion of  our  standard  varieties  of  potatoes  and  points  out 
many  unnecessary  synonyms.  The  reader  is  referred 
to  this  bulletin  for  this  storehouse  of  information  on 
potato  varieties. 

Stuart  gives  the  following  classification  key : 

Stuart's  cldssificution 
Group  1.  —  Cobbler. 

Tubers  :  Roundish ;  skin  creamy  white. 

Sprouts :  Base,  leaf  scales  and  tips  slightly  or  distinctly  tinged 
with  reddish  violet  or  magenta.     In  many  cases  the  color  is 
absent. 
Flowers :  Light  rose-purple ;     under  intense  heat  may  be  almost 
white. 


28  The  Potato 

Group  2.  —  Triumph, 

Tubers :  Roundish ;  skin  creamy  white,  with  more  or  less  numer- 
ous splashes  of  red,  or  carmine,  or  solid  red;  maturing  very 
early. 

Sprouts :  Base,  leaf  scales  and  tips  more  or  less  deeply  suffused 
with  reddish  violet. 

Flowers  :  Very  light  rose-purple. 

Group  3.  —  Early  Michigan. 

Tubers :  Oblong  or  elongate-flattened ;  skin  white  or  creamy 
white,  occasionally  suffused  with  pink  around  bud-eye  cluster 
in  Early  Albino. 

Sprouts  :  Base  light  rose-piu-ple ;  tips  creamy  or  light  rose-purple. 

Flowers :  Wliite. 


Group  4.  —  Rose  Group. 

Tubers :  Elongated  or  oblong,  usually  flattish  at  the  center  and 
tapering  gradually  toward  each  end  ;  stem  and  seed  end  rather 
blunt.  Skin  smooth,  flesh  color.  Flesh  creamy  white,  some- 
times streaked  with  red. 

Sprouts :  Rather  long,  medium  thick,  and  usually  clearly  tinted 
with  rose-lilac. 


Group  5.  —  Early  Ohio  Group. 

Tubers :  Round-oblong  with  full,  rounded  seed  and  stem  ends. 

Eyes  numerous  and  rather  shallow.     Skin  or  flesh  light  pink 

with  a  deeper  color  around  the  eyes. 
Sprouts :  Short,  much  enlarged  at  the  base,  color  varying  from 

carmine-violet  to  violet-lilac  or  magenta-lilac. 


Group  6.  —  Hebron  Group. 

Tubers :  Elongated,  somewhat  flattened,  \vitli  rather  blunt  ends, 
occasionally  spindle  shape.  Eyes  numerous.  Skin  creamy 
white,  more  or  less  clouded  with  flesh  color  or  light  pink. 

Sprouts  :   Very  similar  to  those  of  the  Early  Rose  Group. 


Description  and  Classification  29 

Group  7.  —  Burbank  Group. 

Tubers :  Long,  cylindrical  or  slightly  flattened  in  shape.  Eyes 
numerous  and  rather  shallow.  Skin  white  to  dull  white, 
smooth  to  glistening,  or  sometimes  russeted. 

Sprouts  :   Base  creamy  wliite  or  faintly  tinged  with  magenta. 

Flowers :  Wliite. 

Group  8.  —  Green  Mountain  Group. 

Tubers :    Broadly    roundish-flattened    to    distinctly    oblong-flat- 
tened ;  ends  usually  blunt,  especially  the  seed  end.     Eyes  rather 
shallow.     Skin  dull  creamy  white,  more  or  less  netted. 
Sprouts  :  Rather  short  and  stubby.     Wliite  or  faintly  tinged. 
Flowers :  White. 

Group  9.  —  Rural  Group. 

Tubers :  Round-flattened  to  broadly  roundish  —  oblong  or  dis- 
tinctly oblong.  Eyes  few ;  very  shallow.  Skin  creamy  white 
and  occasionally  netted. 

Sprouts :  Short,  base  enlarged,  dull  white. 

Flowers :  Of  fair  size.  Central  portion  of  corolla  deep  violet- 
purple,  shading  to  a  lighter  tone  toward  outside  edge. 

Group  10.  —  Pearl. 

Tubers  :  Round-flattened  to  heart-shape  flattened,  usually  heavily 

shouldered ;    skin  dull  white,  dull  russet,  or  brownish  white  in 

section  1  or  a  deep  bluish  purple  in  section  2. 
Sprouts :  Section  1  —  base,  leaf  scales  and   tips  usually  faintly 

tinged  with  lilac ;    section  2  —  base,  leaf  scales  and  tips  vinous 

mauve. 
Flowers :  White. 

Group  11. — Peachblow. 

Tubers  :  Round  to  round-flattened  or  round-oblong ;  skin  creamy 
white,  splashed  with  crimson  or  solid  pink ;  eyes  usually  bright 
carmine.     Includes  some  early-maturing  varieties. 

Sprouts :  Base,  leaf  scales  and  tips  more  or  less  suffused  with 
reddish  violet. 

Flowers:  Purple. 


30  The  Potato 

Group  types  according  to  Fitch 

Group  1.  —  Rural. 

Tuber  shape  :   Wide  and  flat  types  when  at  best.     Ends  rounded 

much  hke  stem  and  usually  not  recessed.     (See  Fig.  7.) 
Tuber  and  eye  color :     Blinds,  white.     First  sprouts  yellow  or 

waxy  white  with  bluish  violet  tips  which  change,  on  exposure 

to  light,  to  dark  or  dull  purple. 
Root  stubs  :  Yellowish  white ;   free  from  purple. 
Stem  :  Erect  and  touched  with  brownish  purple. 
Foliage  :   Green,  darkened  by  the  purple,  and  in  state  much  more 

acrid  than  "all-green"  foliage. 
Blossom  :  Bluish  violet- white. 

Group  2.  —  Early  Ohio. 

Tuber  shape :     Somewhat  flattened  and  slightly  tapering,  with 

stem  end  a  least  bit  recessed.     Eyes  are  unevenly  distributed 

and  numerous.     (See  Fig.  7.) 
Tuber  and  eye  color :  Skin  brownish  pink,  almost  white  to  red, 

changing,  on  long  exposure  to  light,  to  a  weathered  gray  brown. 

First  sprouts  are  white  or  greenish  white  with  lilac  tips. 
Foliage :  Medium  green. 
Blossoms :  Lilac-white. 

Group  3. — Irish  Cobbler. 

Tuber  shape :  The  finest  type  is  flat  and  wide  like  good  Rurals 
but  there  is  a  very  distinct  round,  rough,  deep-eyed  type  formed 
in  poorer  conditions.  In  some  cases  large  types  are  pear 
shaped  and  rough  like  the  largest  Rurals  and  may  combine 
the  pear  shape  with  the  heavy  eyebrow  types  of  the  Rural. 

Tuber  and  eye  color :  Skin  smooth  yellowish  white,  changing  in 
the  light  to  dull  olive-green  with  a  suggestion  of  blue.  Blinds, 
white.     Sprout-leaves,  hairy,  light  green. 

Blossoms :  Pink  with  white  tips  on  petals.  Wliite  blossoms  not 
found  on  Cobblers. 

Group  4.  —  Green  Mountain. 
Tuber  shape :    The  waisted  or  dumb-bell  type  is  characteristic. 
Stem  end  somewhat  recessed.     (See  Fig.  7.) 


Description  and  Classification  31 

Tuber  and  eye  color :  A  fine  smooth  and  quite  brown  netting  is  a 

feature  of  many  of  the  tubers.     An  "all-white"  variety. 
Foliage :  Bright  green. 
Blossoms :  White.     Buds  yellow. 

Group  5.  —  Burbank. 

Tuber  shape  :    Long,  largest  at  center.     Best  type,  shorter,  wide, 

and  flattened.     Poor  type,   spindle  shaped.     Stem  end  flush. 

Eyes  shallow  or  flush.     In  poor  conditions  very  subject  to  knots. 

(See  Fig.  7.) 
Tuber  and  eye  color :  Blinds,   white.     Skin  white  changing  in 

light  to  greenish  gray  brown.     First  sprouts  white  with  light 

green  tips. 
Foliage :  Bright  green. 
Blossoms  :  White.     Buds  yellow. 

Group  6.  —  Peerless  or  Pearl. 

Tuber  and  eye  color :  Skin,  white,  or  if  ripened  well,  brownish 
white,  coarsely  cracked.  Skin  turns  dull  green  in  light.  (See 
Fig.  7.) 

Blossoms :  White,  when  borne.     Buds,  white  or  greenish  white. 

Stem  and  foliage  :  Vigorous,  bright  green. 

Group  7.  —  Bliss  Triumph. 

Tuber  shape :  More  or  less  roughly  globular,  recessed  stem. 
Large  tubers  somewhat  oval  or  nosy.     (See  Fig.  7.) 

Tuber  and  eye  color :  Pink  to  red-brown  skin  changing  in  light 
to  grayish  red  brown.  Blinds,  pink  to  red  brown.  Sprout- 
leaves,  dark  apple-green. 

Groups  according  to  Kohler 

Group  L — Tuberosum  Group. 

Characterized  by  foliage  of  the  wild  Solanum  type.  Tubers  of 
varying  shape,  usually  with  rather  deep  eyes;  below  medium 
in  size. 

Foliage  relatively  resistant  to  disease. 


32  The  Potato 


Group  2.  —  Rural  Group. 


Rural  New  Yorker  is  the  type  of  the  group.  Tubers  character- 
istically short,  smooth  and  flattened.  Skin  white.  Eyes 
generally  shallow. 


Group  3.  —  Leo  Group. 

Plants  upright  in  habit;     little  or  no  purple  in  stems.     Tubers 
roundish  or  somewhat  elongated  with  uneven  siu-face. 


Group  4.  —  Woltman  Group. 

Plants  medium  erect;     foliage  fairly  dense.     Tubers  similar  to 
those  of  Leo  group.     Group  not  very  well  defined. 


Group  5.  —  Endurance  Group. 

Plants  very  recumbent ;  leaves  pure  green.     Tubers  light  in  color ; 
elongated  to  medium  in  length. 


Group  6.  —  Factor  Group. 

Plants  fairly  erect,  with  dense  foliage.     Tubers  generally  roundish 
or  short  elliptical ;  comparatively  even  surface. 


Group  7.  —  Sharpe's  Express. 

Plants  moderately  erect;  foliage  dark  green.  Tubers  rounded 
or  slightly  elongated  and  surface  comparatively  even.  Flowers 
white. 


Group  8.  —  Green  Mountain  Group. 

Plants  medium  upright ;  stem  free  from  purple.  Tubers  medium 
in  length  with  a  tendency  toward  oblong  form;  white  and 
slightly  netted  skin.     Eyes  sunken  somewhat. 


Plate  II.  —  Types  of  potato  tubers,  as  illustrated  by  the  Wisconsin 

Experiment  Station. 

A  careful  selection  of  seed  for  a  few  years  will  gradually  elinainate  these 

undesirable  types. 


Description  and  Classification  33 

Group  9.  —  Michigan  Group. 

Michigan  variety  typical  of  the  group.  Tubers  somewhat  elon- 
gated; skin  fairly  smooth.  A  composite  group  with  char- 
acters not  well  defined. 

Group  10.  —  Ohio  Group. 

The  Early  Ohio  is  typical  of  this  group.  Tubers  oval  in  shape 
and  only  slightly  compressed;  eyes  numerous  and  usually 
shallow.     Sm"face  quite  even. 

Group  11.  —  Cobbler  Group. 

Plants  upright  in  habit.  Tubers  white,  pink  or  red;  variable 
in  shape  and  size. 

Groups  according  to  Milward 
Group  1.  —  Round  White  Group. 

Tubers  :  round  to  oval  and  slightly  flattened.     Surface  generally 

netted.     Skin  white  and  flesh  white. 
Flowers  :  white  or  purple. 

Group  2.  —  Long  White  Group. 

Tubers :  Long  oblong  in  shajje  and  sometimes  flattened.  Skin 
and  flesh  white. 

Tabulation  of  varieties 

The  varieties  of  potatoes  mentioned  and  described  by 
Stuart,  Milward,  Kohler  and  Fitch  have  been  brought 
together  in  one  table  for  convenience.  Each  variety  so 
far  as  possible  has  been  classified  by  naming  the  group 
into  which  it  has  been  placed  by  one  or  more  of  the  authors 
named.  In  this  way,  it  is  easy  for  any  person  to  get  an 
idea  of  a  variety  if  he  is  unfamiliar  with  it  by  referring 
to  the  description  of  the  group  into  which  the  variety  is 
placed : 


34 


The  Potato 


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Description  and  Classification 


35 


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36 


The  Potato 


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Description  and  Classification 


37 


The  Potato 


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Description  and  Classification 


39 


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40 


The  Potato 


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Description  and  Classification 


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42 


The  Potato 


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Description  and  Classification  43 

Synonyms 

Frequently  potatoes  belonging  to  well-recognized  va- 
rieties are  renamed  and  sold  as  distinctly  new  sorts. 
This  practice  may  be  due  to  the  fact  that  the  seedsman, 
or  the  grower,  is  not  familiar  with  all  the  standard  va- 
rieties ;  or  it  may  be  a  fraudulent  attempt  to  induce  the 
farmer  to  pay  a  high  price  for  seed  of  a  supposedly  new 
and  superior  variety.  Then,  too,  the  same  type  may 
arise  in  different  parts  of  the  country  at  about  the  same 
time  and  be  given  different  names  in  each  locality.  Be- 
cause of  these  conditions  we  often  have  one  variety  mas- 
querading under  a  number  of  different  trade  names.  It 
is  desirable  that  a  single  name  be  chosen  for  each  distinct 
type,  and  that  that  name  alone  be  used  to  designate 
tubers  of  the  standardized  type.  The  following  list  of 
synonyms,  adapted  from  Stuart,  may  be  found  helpful 
in  straightening  out  variety  names : 

Synonym  Preferred  Name 

Acme  Early  Acme 

Black  Mercer  Black  Chenango 

Bliss  Triumph  Triumph 

Bhie  Noses  Mercer 

Boston  Market  Early  Sebec 

Bresee's  No.  2  Bresee's  Prolific 

Bresee's  No.  4  King  of  the  Earlies 

Bresee's  No.  6  Peerless 

Bruce's  White  Beauty  White  Beauty 

California  Russet  Russet  Burbank 

Chenango  Mercer 

Chenango  Wliite  Mercer 

Early  Bovee  Bovee 

Early  Henry  Early  Shaw 

Early  Hunt  Triumph 

Early  Pinkeye  Dykeman 


44 


The  Potato 


Synonym 

Early  Sunlight 

Early  Victor 

Early  Wenvvell 

Ensign  Bagley 

Farmer  Hasting 

Improved  Early  Rose 

Improved  Manistee 

Junior  Pride 

Knowles's  Big  Cropper 

La  Plata  Red 

Late  Hoosier 

Lookout  Mountain 

Maine  Rose 

Merino 

Meshanock 

Mashannocks 

Nephannocks 

Neshannocks 

New  Blush 

New  Minister 

Nishenock 

Page's  Extra  Early  Surprise 

Peachblow 

Peachblow 

Philadelphia 

Pride  of  the  South 

Queen  of  the  West 

Red  Bliss 

Red  Mercer 

Red  Six  Weeks 

Rose  No.  4 

Round  Pinkeye 

Rural  New  Yorker  (No.  1) 

Rural  Russet 

Six  Weeks 

Spanish 

Stray  Beauty 

Vermont  Champion 


Preferred  Name 

Sunlight 

Victor 

Wendell 

Clark's  Pride 

Farmer 

Early  Rose 

Early  Manistee 

Wliite  Triumph 

Knowles 

Long  Red 

McCormick 

McCormick 

Early  Maine 

Long  Red 

Mercer 

Mercer 

Mercer 

Mercer 

Rm-al  Blush 

Minister 

Mercer 

Early  Surprise 

Jersey  Peachblow 

Western  Red 

Mercer 

White  Triumph 

Maggie  Murphy 

Triumph 

Long  Red 

Triumph 

Spaulding  No.  4 

Dykeman 

Carman  No.  1 

Late  Petoskey 

Early  Six  Weeks 

Long  Red 

Triumph 

Champion 


Description  and  Classification  45 

Synonym  Preferred  Name 

Weld's  Jumbo  Jumbo 

White  Bliss  Pride  of  the  South 

White  Chenango  Mercer 

White  Early  Ohio  White  Ohio 

White  Elephant  Late  Beauty  of  Hebron 

White  Meshannock  White  Mercer 

White  Triumph  Pride  of  the  South 

Willard  Seedling  WiUard 


DESCEIPTION    OF   TYPICAL  VARIETIES 

Below  are  given  brief  descriptions  of  the  more  popular 
varieties.  These  descriptions  have  been  taken  largely 
from  Stuart :  ^ 

Burbank.  —  Originated  by  Luther  Burbank  in  1873 ;  claimed  to 
be  a  seedling  of  the  Early  Rose.  Season  medium  late.  Tubers 
large,  round,  long;  eyes  shallow,  but  rather  numerous;  skin  nearly 
smooth,  white;  flesh  firm,  fine  grained,  of  excellent  flavor  when 
cooked. 

Carman  No.  1  (Rural  New  Yorker  No.  1). — Originated  by 
E.  S.  Carman  in  1889.  Seedling  of  other  seedlings.  Season  medium. 
Very  few,  shallow  eyes ;  quality  excellent ;  flesh  white.  Vines  very 
stocky. 

Country  Gentleman.  —  Originated  by  G.  W.  P.  Jerrard  Co.  Sea- 
son medium  late.  Vines  of  medium  vigor  and  spreading  habit; 
flowers  white.  Tubers  long,  cylindrical ;  eyes  medium ;  skin  Hght 
buff;  flesh  white. 

Early  Rose.  —  Originated  by  Albert  Bresee  in  1861.  Season 
early.  Vines  stout,  erect;  leaves  large.  Tubers  quite  smooth; 
nearly  cylindrical,  tapering  toward  each  end;  eyes  shallow;  skin 
thin,  tough,  and  of  a  dull  blush  color ;  flesh  white,  solid,  brittle. 

Green  Mountain.  —  Originated  by  O.  H.  Alexander  in  1878. 
Claimed  to  be  a  seedling  for  a  cross  between  Dunmore  and  Excel- 
sior. Season  medium  late.  Vines  vigorous,  with  dark  green 
foliage.     Tubers  short  and  chunky,  flattened,   not  very  regular; 

1  Stuart,  Wm.     U.  S.  D.  A.,  Prof.  Paper,  Bui.  176,  1915. 


46  The  Potato 

eyes  sometimes  considerably  depressed;    skin  nearly  white;  flesh 
fine  grained. 

Irish  Cobbler.  —  Of  unknown  origin.  Season  extra  early. 
Tubers  nearly  round,  large ;  eyes  good ;  skin  russet,  finely  netted ; 
flesh  white.     Similar  or  identical  with  variety  Eureka. 

Pearl,  Midseason.  —  Vines  strong,  medium  to  large ;  stems  me- 
dium dark  green,  rather  stocky;  erect  at  first,  bending  over  as  the 
season  advances.  Leaves  large,  flat,  medium  dark  green.  Flowers 
wliite.  Tubers  medium  to  large,  round-flattened  to  heart-shaped, 
flattened,  usually  broader  at  the  stem  end ;  pinkish  tinge  about  the 
eyes,  especially  when  freshly  dug;  skin  dull  white  or  light  russet, 
usually  roughened  or  cracked ;   flesh  solid  and  quite  heavy. 

Rural  New  Yorker  No.  2.  —  Originated  by  E.  S.  Carman.  Intro- 
duced into  trade  about  1889.  Season  medium  late.  Vines  tlirifty 
and  strong.  Tubers  oblong,  inclined  to  round  or  round-oval,  rather 
flattened ;  eyes  few,  shallow ;   skin  pure  white  netted ;  flesh  wliite. 

Sir  Walter  Raleigh.  —  Originated  by  E.  S.  Carman.  Claimed  to 
be  a  seedling  of  Rural  New  Yorker  No.  2.  Introduced  into  trade 
in  1897.  Vines  similar  in  habit  and  color  of  flowers  to  those  of 
Rural  New  Yorker,  No.  2,  but  color  of  stems  not  as  pronounced. 
Color  of  flesh  and  skin  of  tubers  is  the  same;  quality  better  than 
that  of  Rural  New  Yorker  No.  2. 


REFERENCES 

Baker.     A  Review  of  Tuber-bearing  Species  of  Solanum.     Linn. 

Soc.  Journal  Bot.,  20 :    pp.  489-507,  pis. 
Fitch,  C.  L. 

Identification  of  Potato  Varieties.     Iowa  Extension  Bui.  20.     1914. 
KOHLER,  A.  R. 

Potato   Experiments   and  Studies  at   University   Farm  in   1909. 
University  of  Minnesota  Bui.  118.     April,  1910. 
MiLWARD,  J.  G. 

Conmiercial  Varieties  of  Potatoes  for  Wisconsin.      University  of 
Wisconsin  Bui.  225.     July,  1912. 
Percival,  John.     Agricultural  Botany,  pp.  439-451. 
Stuart,  Wm. 

Group  Classification  and  Varietal  Descriptions  of  Some  American 
Potatoes.     U.  S.  D.  A.  Bui.  176.     March  27th,  1915. 


CHAPTER  IV 
POTATO  BREEDING 

The  cultivated  potato  of  to-day  has  undergone  a  re- 
markable change  since  its  first  introduction  into  Europe 
by  the  Spaniards.  Some  of  this  change  has  been  brought 
about  by  better  cultivation,  but  most  of  it  is  due  to  breed- 
ing. The  tubers  of  the  wild  »S.  tuberosum  were  small 
and  attracted  little  attention.  Heriot,  in  his  report  on 
Virginia,  describes  the  plant  "with  roots  as  large  as  a 
walnut  and  others  much  larger ;  they  grow  in  damp  soil, 
many  hanging  together  as  if  tied  on  ropes."  The  potato 
as  we  know  it  has  been  developed  by  means  of  conscious 
and  unconscious  selection  and  by  hybridization  with 
other  species.  The  modern  potato  has  not  only  been 
much  changed  by  breeding,  but  it  is  now  grown  in  widely 
different  surroundings  which  produce  various  changes 
in  the  tubers. 

There  are  three  foundations  on  which  the  increased 
productivity  of  crops  rests  —  the  enrichment  of  the  land ; 
its  tillage  and  care ;  and  the  production  of  better  varie- 
ties and  strains.  The  first  two  are  concerned  with  the 
environment  of  the  crop,  such  as  cultivation,  fertilization, 
freedom  from  insects,  disease  and  so  forth,  and  the  last 
with  its  heredity.  We  have  long  given  attention  to 
environment;  now  we  are  studying  heredity  with  new 
enthusiasm  and  purpose.  One  of  the  "signs  of  the 
47 


48  The  Potato 

times"  is  the  attention  that  is  being  given  to  the  practi- 
cal breeding  of  crops.  We  have  learned  that  good  seed 
is  a  necessary  accompaniment  to  high  fertility  and  good 
care  and  also  the  desirability  of  different  varieties  adapted 
to  varying  needs  of  soil;  climate  and  man. 

These  wild  forms  have  been  taken,  in  most  cases,  from 
their  original  habitats  and  placed  under  conditions  of 
soil,  temperature  and  moisture  to  which  they  are  not 
accustomed.  Here  selection  must  not  only  modify  the 
plants  better  to  meet  the  wants  of  man,  but  they  must 
become  adapted  to  their  new  environment.  Most 
plants  are  very  flexible  and  finally  become  adapted  to  a 
variety  of  conditions.  This  is  evidenced  by  the  very 
large  number  of  varieties  of  which  most  of  our  cultivated 
plants  consist. 

Results  of  careful  and  systematic  breeding  are  accu- 
mulating rapidly  with  very  many  kinds  of  plants.  The 
results  of  all  this  work  will  probably  enable  us,  even- 
tually, to  formulate  somewhat  definite  statements  as  to 
how  to  proceed  to  secure  desired  results.  Considerable 
evidence  is  already  at  hand,  but  on  the  whole  the  methods 
of  breeding  are  still  somewhat  empirical. 

All  of  our  cultivated  plants  have  come  from  wild  forms. 
Man  has  seen  in  them  possibilities  of  usefulness,  and  he 
has  chosen  year  after  year  the  ones  which  better  serve 
his  purpose.  This  constant  selection  has  in  the  course  of 
time  produced  profound  changes  in  our  plants. 

IDEALS  FOR  THE  POTATO  CROP 

Plant-breeding  is  worthy  of  the  name  only  as  it  sets 
definite  ideals  and  is  able  to  attain  them.  Merely  to 
produce  new  varieties  is  of  no  merit.     We  must  give  up 


Potato  Breeding  49 

the  production  of  mere  novelties  unless  the  new  variety 
possesses  some  property  which  makes  a  real  contribution 
to  our  present  varieties. 

It  is  unfair  and  dishonest  consciously  to  rename  old 
varieties  under  the  pretense  of  producing  something  new. 
Our  list  of  varieties  contains  many  synonyms,  and  these 
should  not  be  consciously  increased. 

In  general,  the  improvement  of  our  present  standard 
varieties  offers  greater  opportunities  for  the  increased 
efficiency  of  the  new  generation  of  plants  than  the  pro- 
duction of  entirely  new  varieties. 

Ideals  for  the  perfect  potato  will  change  in  the  different 
localities.  Certain  attributes,  however,  are  universally 
desired.     These  are  as  follows  : 

(1)  High  yield. 

(2)  Good  quality. 

(3)  Disease-resisting  capabilities. 

(4)  Good  keeping  qualities. 

(5)  Good  color  of  flesh  and  skin. 

(6)  Skin  of  desirable  texture. 

(7)  Tubers  of  good  shape. 

(8)  Shallow  eyes,  relatively  few  in  number. 

(9)  Maturing  in  season  common  to  the  variety. 

(10)  Upright,  vigorous  plants. 

(11)  Heavy  leaf  cuticle. 

(12)  No  tendency  to  make  second  growth. 

(13)  Trueness  to  type  of  variety  grown. 

High  yield  is  essential  if  the  grower  expects  to  continue 
raising  potatoes  for  market.  In  aiming  to  secure  high 
yield,  however,  we  should  remember  that  there  are  many 
other  factors  which  determine  the  marketability  and 
price  of  the  product.     Tubers   of  inferior   quality,    size 


50  The  Potato 

and  the  like  are  not  of  great  ^•alue  even  in  large  quan- 
tities. 

From  the  consumer's  point  of  view,  quality  is  highly- 
important.  The  grower  would  do  well  to  keep  his  pota- 
toes up  to  standard  in  this  respect.  Potatoes  intended 
for  human  consumption  should  have  a  mealy  flesh  when 
boiled  or  baked.  Up  to  a  certain  limit  the  quality 
improves  with  an  increase  in  starch  content.  Potatoes 
to  be  used  for  the  production  of  alcohol  need  be  of  no 
particular  quality  from  the  culinary  standpoint. 

There  are  no  disease-proof  varieties,  but  some  are 
more  resistant  than  others.  Resistance  is  more  impor- 
tant in  the  East  than  in  the  Mississippi  Valley. 

It  is  necessary  to  store  potatoes  for  a  long  period,  to 
supply  the  demands  between  crops.  If  the  keeping 
qualities  of  a  strain  are  poor,  there  are  fewer  potatoes 
which  can  be  sold  in  the  spring.  In  a  sense,  then,  poor 
keeping  quality  is  a  factor  which  decreases  yield. 

The  ideal  color  of  skin  and  flesh  will  depend  largely 
upon  market  preferences.  In  general  a  yellow  skin  and 
white  flesh  are  desired.  In  the  South,  the  red-  or  pink- 
skinned  varieties  are  in  favor.  Because  of  the  red  color 
of  some  weak  varieties,  growers  are  likely  to  be  skeptical 
of  all  colored  varieties. 

The  skin  may  be  thick,  medium,  or  thin.  Whew  grown 
in  sandy  soil,  the  skin  is  usually  smoother  than  when 
grown  in  heavy  loams.  A  netted  and  slightly  rough  skin 
is  preferred,  many  believing  that  it  indicates  proper 
maturity  and  good  quality. 

Flat-round  or  flat-oval  tubers  are  better  than  the  spher- 
ical, as  the  cortical  and  outer  medullary  layers,  containing 
the  starch,  are  relatively  larger.  Also  a  flat  tuber  bakes 
better,  because  the  center  is  not  too  far  from  the  outside. 


^^^. 


Potato  Breeding  51 

Deep  eyes  cause  waste  in  peeling.  They  hold  mois- 
ture, thereby  causing  decay  in  storage.  The  tuber 
should  have  enough  eyes  to  make  good  seed,  but  not  so 
many  as  to  make  peeling  difficult. 

Early  varieties  may  mature  in  70  to  90  days  after 
planting;  second-earlier  in  90  to  130  days;  and  late 
varieties  may  continue  to  grow  for  200  days.  It  is  im- 
portant to  choose  a  variety  adapted  to  the  locality. 

The  haulm  and  leaf  are  considered  more  important 
than  formerly.  Large  haulms  require  wider  spacing  of 
plants  and  greater  expense  for  spraying.  Short-haulmed, 
upright,  heavy-leafed  tops  are  not  as  susceptible  to  dis- 
ease as  the  prostrate  types.  The  upright  types  are  more 
likely  to  suffer  during  very  dry  spells,  however,  because 
the  tops  do  not  prevent  the  evaporation  of  moisture  from 
the  soil  as  do  those  of  the  more  prone  types.  Care  should 
be  exercised  to  select  a  variety  which  is  well  suited  to 
local  conditions  and  which  will  grow  vigorously.  Dif- 
ferences in  vigor  will  be  noted  in  different  strains  of  the 
same  variety. 

Leaves  with  thick  cuticles  are  not  as  easily  penetrated 
by  disease  spores. 

When  a  period  of  drought  is  followed  by  a  wet  spell, 
second  growth  is  likely  to  begin.  The  dry  weather 
checks  growth  and  the  tubers  begin  to  mature.  Subse- 
quent wet  weather  restarts  growth.  Such  abnormalities 
should  be  discarded  in  selecting  seed. 

It  is  essential  that  the  seed  be  as  represented.  None 
but  experts  can  tell  the  different  varieties  apart,  so  seed 
should  be  obtained  from  a  reliable  source. 

The  half-tone  illustrations  in  Plates  III  to  VII  show 
some  of  the  desirable  potato  forms,  and  also  results  in 
breeding. 


52  The  Potato 

Use  of  score-card 

A  score-card  presents  in  a  logically  arranged,  tabular 
form  the  different  factors  which  make  up  an  ideal  potato. 
These  factors  are  given  relative  importance  or  weight  by 
means  of  percentage  numbers,  the  sum  of  which  is  100. 
One  should  make  frequent  use  of  a  score  card  to  familiar- 
ize himself  with  all  details  and  to  compare  his  product 
with  the  theoretical  ideal  product,  which  it  describes. 

The  score-card  should  be  studied  so  as  to  establish  the 
ideal  of  the  desired  variety  firmly  in  mind  before  any 
attempt  is  made  at  improvement. 

■  When  breeding  a  crop,  special  attention  should  be  paid 
to  the  details.  The  proper  combination  of  the  little  and 
usually  overlooked  points  makes  the  perfect  crop. 

It  is  important,  further,  to  bear  in  mind  the  fact  that 
a  variety  which  is  merely  as  good  as  any  other  in  culti- 
vation is  not  worth  introducing.  It  should  be  better  in 
some  particular  than  any  other  in  existence.  The  oper- 
ator must  know  the  points  of  his  plant,  as  an  expert  stock- 
breeder knows  the  points  of  an  animal,  and  he  must 
possess  the  rare  judgment  to  determine  which  charac- 
ters are  most  likely  to  reappear  in  the  offspring.  Inas- 
much as  a  person  can  be  an  expert  in  only  a  few  plants, 
it  follows  that  he  cannot  expect  satisfactory  results  in 
breeding  any  species  which  may  chance  to  come  before 
him.  Persistent  and  uniform  effort,  continued  over  a 
series  of  years,  is  generally  demanded  for  the  production 
of  really  valuable  varieties.  Thus  it  often  happens  that 
one  man  excels  all  competitors  in  breeding  a  particular 
class  of  plants.  If  the  operator  —  himself  an  expert 
judge  of  the  plant  with  which  he  deals  —  chooses  his 
seeds  with  care  and  discrimination,  and  then  proposes, 


Plate  V.  — Typical  early  and  late  potatoes.     Top,  Irish  Cobbler  (early). 
Bottom,  Rural  New  Yorker  (late). 


Potato  Breeding 


53 


if  need  be,  to  follow  up  his  work  generation  after  genera- 
tion by  means  of  selection,  the  work  becomes  plant- 
breeding  of  the  highest  type. 

First  of  all,  therefore,  the  operator  must  know  what  he 
is  likely  to  secure,  and  what  will  probably  be  worth  se- 
curing. ]Most  persons,  however,  begin  at  the  other  end  of 
the  problem,  —  they  get  what  they  can,  and  then  let  the 
public  judge  whether  the  effort  has  been  worth  the  while. 

The  following  score-card  has  been  adopted  by  the 
New  York  State  Potato  Association : 

Potato  Score-card 


Conformity  to 

Varietal  Type 

100  Points 

Conformity  to 

Market  Demand 

100  Points 

Perfect 

Perfect 

Uniformity 

Blemishes  and  disease       .     .     . 

Shape    

Size 

Quality  of  flesh 

Depth  and  frequency  of  eyes    . 
Color  and  texture  of  skin     .     . 

20 
15 

15 
10 
10 
15 
15 

20 
20 
15 
15 
10 
10 
10 

100 

100 

This  score-card  is  arranged  with  the  idea  of  empha- 
sizing the  more  important  characteristics  to  be  con- 
sidered in  selecting  potatoes  both  true  to  varietal  type 
and  in  accordance  with  market  demands.  These  two 
sets  of  qualifications  are  in  many  cases  quite  distinct.  It 
is,  therefore,  true  that  the  variety  which  fulfills  both  of 
these  requirements  is  the  one  that  scores  highest  and  of 
which  production  should  be  encouraged. 


54  The  Potato 

Uniformity.  —  Exhibit  should  be  uniform  in  all  phys- 
ical characteristics. 

Blemishes  and  disease.  —  Should  be  no  evidence  of 
blight,  rot,  grubs,  rhizoctonia,  sunburn,  or  injury  from 
rough  handling. 

Shape.  —  Should  be  typical  of  the  variety.  Market 
demands  a  moderately  oval-flat  or  round-flat  shape. 

Size.  —  Should  be  typical  of  the  variety.  Market 
demands  a  medium-sized  potato. 

Quality  of  flesh.  —  Should  be  true  of  the  variety. 
Market  requires  a  fine-textured  flesh  of  light  color,  free 
from  excess  moisture  and  from  hollow  or  dark  spots. 

Depth  and  frequency  of  eyes.  —  Should  be  typical  of  the 
variety.     Market  demands  few  and  shallow  eyes. 

Color  and  texture  of  skill.  —  Should  be  typical  of  the 
variety.  Market  demands  a  thin,  smooth  skin.  White- 
skinned  varieties  are  preferable  in  most  markets. 

POSSIBILITIES   OF   IMPROVING  THE   POTATO 

Even  though  the  potato  has  been  in  cultivation  for 
centuries,  further  improvement  is  by  no  means  impos- 
sible. It  responds  very  quickly  to  breeding.  Most 
varieties  are  very  impure  and  contain  various  types. 
The  first  task  of  the  breeder  is  to  become  thoroughly 
acquainted  with  his  plants  so  as  to  discard  the  poor 
plants  and  save  the  good  ones  for  future  planting.  If 
this  is  done  for  a  few  years,  the  average  yield  of  the 
crop  and  its  uniformity  will  be  greatly  benefited. 

The  hill  selection  of  potatoes  is  not  generally  practiced 
and  as  a  consequence  the  varieties  soon  deteriorate  and  run 
out.  This  deterioration  could  be  easily  prevented  by  pay- 
ing careful  attention  to  planting  seed  from  the  best  hills. 


Potato  Breeding  55 

It  must  not  be  forgotten  that  potatoes  are  now  grown 
in  regions  where  the  cHmate  is  not  entirely  congenial 
to  them.  This  constant  action  of  a  somewhat  mifavor- 
able  climate  will  also  cause  them  to  degenerate  if  not 
counteracted  by  seed  selection. 

Careful  experiments  have  been  conducted  with  pota- 
toes in  which  the  offspring  of  different  tubers  are  planted 
and  recorded  separately.  Many  of  these  progenies  seem 
to  degenerate  completely,  indicating  that  some  degen- 
erative factor,  still  unknown,  is  constantly  at  work. 
This  deterioration  is  partially  due  to  disease,  without 
doubt,  but  some  of  it  also  is  of  a  physiological  nature. 

The  yields  of  any  field  or  the  average  yields  of  any 
locality  or  of  an  entire  state  are  far  below  what  they 
should  be.  This  is  due  to  two  causes :  the  conditions 
surrounding  the  crop  have  not  been  the  best  —  perhaps 
insufficient  food  supply  or  water  or  poor  soil;  and  sec- 
ondly, the  absence  of  seed  selection  has  produced  a  poor 
stand  of  plants,  many  of  which  probably  give  low  yields. 
By  proper  attention  to  fertilization,  spraying  and  seed 
selection,  the  yield  may  often  be  doubled  or  trebled. 
Perhaps  we  can  never  expect  the  high  yields  to  the  acre 
obtained  in  Europe  because  of  our  hot  dry  climate 
(see  Chapter  I), 

If  seed  selection  becomes  generally  practiced,  with 
its  accompanying  increase  in  yields,  vast  consequences 
may  be  looked  for.  If  all  of  the  hills  on  an  acre  of  pota- 
toes planted  in  the  ordinary  manner  weigh  one-half  a 
pound,  there  will  be  a  yield  of  78  bushels  to  the  acre. 
A  half-pound  hill,  however,  is  very  small.  One  ordinary- 
sized  tuber  will  weigh  more  than  that.  If,  by  means  of 
breeding,  the  average  yield  to  a  hill  is  increased  to  one, 
two  or  three  pounds,  which  is  not  at  all  impossible,  the 


56 


The  Potato 


yields  to  the  acre  will  be  increased  to  156,  312  and  468 
bushels  respectively.  If  this  reasoning  were  applied  to 
all  of  the  potato  fields  in  the  United  States,  the  result 
would  be  almost  unbelievable.  Burbank  has  made  the 
conservative  estimate  that  if  one  tuber  were  added  to  each 
hill,  the  total  resulting  increase  in  the  United  States 
would  be  21,000,000  bushels  yearly. 

The  following  table  gives  the  yields  to  the  acre  from 
hills  of  certain  weights.  It  is  assumed  that  the  hills 
were  18  inches  apart  in  the  rows  and  the  latter  were  3  feet 
apart.     This  rate  of  planting  gives  9372  hills  on  an  acre : 

Table  IX 


Yield  to  the  Hill 

Pekpect  Stand 

90  Per  Cent  Stand 

Pvunda 

Bushels  to  the  Acre 

Bushels  to  the  Acre 

.5 

78.1 

70.29 

1.0 

156.2 

140.58 

1.5 

2.34.3 

210.87 

2.0 

312.4 

281.16 

2.5 

390.5 

351.45 

3.0 

468.6 

421.74 

3.5 

546.7 

492.03 

4.0 

624.8 

562.32 

METHODS   OF   IMPROVEMENT 

Plants  are  improved  in  three  ways :  first,  by  simple 
selection,  that  is,  breeding  from  the  best,  the  object 
being  to  improve  the  present  varieties  rather  than  the 
production  of  new  ones;  second,  to  conduct  extensive 
plantings  for  the  purpose  of  discovering  some  unusually 
good  individuals  or  mutants,  which  may  become  the 
foundation  of  improved  varieties  and  which  subsequently 


ffl 

^b^PSe 

-m 

^ 

1^31^3^^ 

^ 

^l^^^^^^^^^^^^^^^^^^mmmKsr"  "  ■    ^'- 

|||i%... 

mmmsmaa^Km^^^  -.-\>:_^^ 

■Tt  - 

Plate  VI.  —  Breeding  —  Each    group    of    four    plates    represents    the 
progeny  of  a  tuber ;  and  each  plate  is  the  produce  of  a  single  hill. 


Potato  Breeding  57 

require  little  else  of  the  grower  than  their  multiplication  ; 
and  third,  by  crossing  plants  to  combine  the  best  qualities 
of  two  or  more  parents  in  a  new  and  improved  variety. 


Improvement  of  the  'potato  by  selection 

The  principal  method  of  improving  the  potato  is  by 
bud-selection.  Potato  hills  are  very  variable,  and  im- 
provement is  made  by  planting  tubers  from  the  best 
hills.  Many  of  these  apparent  improvements  may  be 
due  to  some  advantage  in  growth,  such  as  increased  fer- 
tility, more  light  or  moisture  and  so  forth.  Of  course, 
this  increase  is  only  transitory,  and  not  being  inherited, 
produces  no  permanent  advancement. 

The  potato,  however,  presents  variations  which  are 
inherited.  These  are  of  two  kinds,  —  smaller  differences 
whose  inheritance  produces  a  gradual  change,  and  large  dif- 
ferences or  so-called  "bud-sports"  or  bud-mutants  which 
immediately  become  the  starting  point  of  new  varieties. 

Potatoes  differ  from  most  farm  crops  in  their  manner 
of  reproduction.  They  are  propagated  vegetatively 
without  the  intervention  of  a  sexual  process  like  corn 
or  wheat.  Each  hill  of  potatoes  comes  from  one  tuber  or 
a  part  of  a  tuber  which  was  the  product  of  one  bud  of  the 
mother  plant.  Hence  the  entire  hill  becomes  a  unit,  and 
hill  selection  is,  in  reality,  bud-selection.  Single  tubers 
cannot  be  said  to  be  units  from  the  breeder's  standpoint. 
Therefore,  it  is  of  supreme  importance  to  take  into  ac- 
count the  yield  of  an  entire  hill  and  not  the  presence  in 
it  of  two  or  three  large  tubers  resulting  in  low  total  yield 
for  the  hill. 

So  far  as  man  is  concerned,  the  origin  of  the  initial 
variation  is  largely  chance,  but  this  start  or  variation 


58  The  Potato 

once  given,  he  has  the  power,  in  most  cases,  to  perpetuate 
it  and  to  modify  its  characters.  There  are  two  very 
different  factors  or  problems  in  the  origination  of  potato 
varieties  by  selection,  —  the  production  of  the  first  de- 
parture or  variation,  and  the  subsequent  breeding  of  it. 

It  is  apparent  that  the  very  first  effort  on  the  part  of 
the  potato-breeder  must  be  to  secure  individual  differ- 
ences. If  the  plants  which  he  grows  are  very  much  alike, 
there  w^ill  be  very  little  hope  of  obtaining  new  varieties. 
He  should,  if  possible,  cause  his  plants  to  vary.  This 
initial  variation  may  usually  be  induced  by  changing  the 
conditions  in  which  the  plant  has  habitually  gro\\ai,  as 
a  change  of  seed,  change  of  soil,  tillage,  varying  the  food 
supply,  crossing  and  the  like.  As  a  matter  of  fact,  how- 
ever, nearly  all  plants  which  have  been  long  cultivated, 
like  the  potato,  are  already  sufficiently  variable  to  afford 
a  starting  point  for  breeding.  The  grower  should  have 
a  vivid  mental  picture  of  the  variety  which  he  desires  to 
obtain;  then  he  should  choose  those  hills  which  most 
nearly  meet  that  ideal. 

Experimental  breeding  has  demonstrated  that  the 
different  varieties  of  farm  and  garden  plants,  as  we  ordi- 
narily know  them,  are  not  entirely  homogeneous  and 
uniform,  but  are  made  up  of  smaller  groups  now  known 
as  "pure  lines."  It  is  ordinarily  understood  that  a  pure 
line  is  the  progeny  of  a  self-fertilized  indi\idual,  that  is, 
one  in  which  all  effects  of  crossing  have  been  eliminated 
by  constant  self-fertilization.  In  potatoes  which  are 
ordinarily  propagated  asexually,  a  pure  tuber  line  would 
be  the  progeny  of  a  single  tuber. 

Experiments  seem  to  demonstrate  that  the  group  of 
individuals  known  as  a  pure  line  vary  much  less  than  the 
variety  as  a  whole,  and  that  selection  of  the  best  indi- 


Potato  Breeding  59 

viduals  within  a  pure  line  has  httle,  if  any,  effect  in  raising 
the  average  of  the  Hne.  Tliis  has  not  been  proved,  by  any 
means,  but  the  indications  are  that  only  a  very  slight  ad- 
vance is  made  by  continued  selection  after  a  pure  line  has 
been  reached,  unless  an  exceptionally  good  individual 
should  arise  whose  progeny  would  constitute  a  new  and 
better  line. 

It  will  now  be  seen  that  the  first  work  in  improving 
potatoes  by  selection  is  to  determine  the  best  tuber  lines 
and  plant  them  for  seed.  This  necessitates  carrying  out 
a  system  of  breeding  whereby  individual  tubers  must 
be  planted  separately  and  properly  labeled  and  their  prog- 
eny kept  separate  for  a  few  years  to  determine  whether 
or  not  the  desirable  plants  transmit  their  qualities  to  fu- 
ture generations  (see  Plate  VI).  This  is  known  as  "pedi- 
gree breeding."  Myers  gives  the  following  table  to  show 
variation  in  the  yielding  capacity  of  different  tubers. 
Each  unit  is  the  product  of  a  different  parental  tuber : 

Table  X 

Unit  Yield  in  Bushels 

No.  TO  THE  Acre 

1 110 

2 220 

3 220 

4 230 

5 280 

6 320 

7 240 

8 230 

9 230 

10 130 

11 210 

12 70 

13 190 

14 190 

15 25 

16 270 


60 


The  Potato 


If  the  first  work  of  breeding  consists  of  separating  out 
pure  lines  and  if  there  is  very  slow  progress  within  these 
lines,  it  is  obvious  that  the  choice  of  individuals  for 
planting  the  first  few  years  is  all-important.  As  large 
fields  as  possible  should  be  grown  to  give  opportunity 
for  all  of  the  best  plants  to  appear. 


Fio.  8.  Potato  yields.  Diagrams  showing  variation  in  yield  of  in- 
dividual rows  of  potatoes  grown  on  special  seed  plots  in  1909.  (Carman 
No.  1,  by  R.  H.  Crosby,  Markham,  Ont.) 


Until  recently,  the  method  of  selection  has  been  to 
choose  from  the  potato  bins  in  the  spring  the  requisite 
amount  of  seed,  using  tubers  having  the  desired  size  and 
shape  but  without  knowledge  of  whether  they  came  from 
high  yielding  strains  or  not.  This  method  of  choosing 
seed   from  year  to  year,  using  merely  the  best  tubers 


«f 

^ 

i« 

^ 

->% 

^ 

fm 

^ 

:^a 

^ 

^'^^'^  1 

Plate  VII.  —  Tubers  with  histories.  Upper,  influence  of  unfavorable 
growing  season,  showing  the  second-growth  tubers  on  the  right  compared 
with  normal  uniform  tubers  on  the  left.  Lower,  Breeding  —  the  im- 
munity and  susceptibility  of  two  tuber  progenies. 


Potato  Breeding 


61 


without  a  knowledge  of  their  ancestry  or  obtaining  a 
test  of  their  producing  power,  is  known  as  "mass-selec- 
tion."    This  method  will  inevitably  lead  to  improvement 


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5    ' 

3     , 

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^,''z,''zs 

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7 

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10 

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Fig.  9.     Continuation  of  Fig.  8. 


because  the  very  poor  hills  will  not  produce  good  tubers, 
and  hence  will  be  eliminated.  But  the  improvement  is  a 
very  slow  one.     In  employing  this  method  of  mass  selec- 


62  The  Potato 

tion,  growers  were  working  blindly  without  knowing  how 
or  when  or  even  whether  they  were  going  to  reach  a  sta- 
bility of  type.  On  the  other  hand  the  method  of  pedi- 
greed culture  or  "individual  selection"  eliminated  the 
fear  of  failure  because  of  the  appearance  of  the  hitherto 
unsurmountable  variations. 

Plants  which  have  any  desired  characteristics  in  com- 
mon may  differ  widely  in  their  ability  to  transmit  these 
characters.  It  is  generally  impossible  for  the  cultivator 
to  determine,  from  the  appearance  of  any  given  progeny, 
the  most  invariable  and  the  most  like  its  parent ;  but  it 
may  be  said  those  individuals  which  grow  up  in  the  most 
usual  or  normal  environments  are  most  likely  to  perpet- 
uate themselves.  A  very  unusual  condition,  as  of  soil, 
moisture  or  exposure,  is  not  easily  imitated  when  provid- 
ing for  the  succeeding  generation,  and  a  return  to  normal 
conditions  of  environment  may  be  expected  to  be  followed 
by  a  more  or  less  complete  return  to  normal  attributes 
on  the  part  of  the  plant.  If  the  same  variation,  therefore, 
were  to  occur  in  plants  growing  under  widely  different 
conditions,  the  operator  who  wishes  to  preserve  the  new 
form  should  take  particular  care  to  select  his  tubers  from 
those  individuals  which  seem  to  have  been  least  influenced 
by  the  immediate  conditions  in  which  they  were  grown. 

The  method  of  individual  selection  or  pedigree  breed- 
ing is  now  universally  accepted  by  the  best  •  breeders. 
In  potato-breeding  it  is  known  as  the  "tuber-unit" 
method,  that  is,  the  progenies  of  individual  tubers  are 
tested  for  a  number  of  years  to  determine  the  best  pure 
lines  which  are  constant  from  year  to  year. 

One  of  the  first  and  best  methods  of  breeding  potatoes 
by  the  tuber-unit  or  pedigree  plan  has  been  devised  by 
H.  J.  Webber.  This  method  is  so  satisfactory,  when 
properly  carried  out,  that  it  is  given  here  in  detail : 


Potato  Breeding  63 

Selection  of  foundation  stock  of  potatoes.  —  Probably  no  crop 
generally  grown  is  more  influenced  by  environment  than  the  potato. 
The  experience  of  growers  indicates  that  a  variety  found  to  be  the 
best  suited  to  local  conditions  on  one  farm  may  not  prove  to  be  the 
variety  best  suited  to  the  conditions  existing  on  an  adjoining  farm. 
It  thus  becomes  desirable  for  any  farmer  who  is  growing  potatoes 
extensively  to  test  varieties  sufficiently  to  determine  which  is  the 
variety  best  suited  to  the  local  conditions  concerned.  This  ordi- 
narily does  not  require  an  extensive  test  as  the  experience  of  growers 
in  a  region  has  usually  shown  the  general  superiority  of  a  com- 
paratively few  varieties,  and  a  test  can  thus  be  limited  to  these  varie- 
ties which  in  general  are  known  to  be  the  best.  The  WTiter  would 
not  urge  this  test  of  varieties,  if  it  were  not  very  important  to  begin 
any  breeding  work  with  the  best  variety  available.  Breeding  work 
requires  so  much  attention  that  it  does  not  pay  to  start  with  an  in- 
ferior variety.  The  first  effort  of  any  one  contemplating  breeding 
with  potatoes  is  thus  to  determine  the  best  foundation  stock  to  use 
for  the  selection  work.  If  the  grower  has  had  extensive  experience 
in  growing  potatoes  and  has  determined  that  a  certain  variety 
gives  the  best  results  under  his  conditions,  he  is  in  a  position  to  start 
the  selection  without  a  further  test  of  varieties. 

Growing  potatoes  for  selection.  —  The  influence  of  the  number  of 
eyes  and  size  of  piece  planted  as  seed  has  so  much  to  do  with  the 
yield  of  the  liill  that  fields  planted  in  the  ordinary  way  are  very 
poorly  adapted  to  begin  the  work  of  selection.  It  is  of  primary  im- 
portance that  the  first  selections  be  of  the  very  highest  type  obtain- 
able, as  it  is  a  common  experience  that  the  first  selection  is  the  most 
important.  Too  much  attention  cannot  be  given  therefore  to  the 
first  selection.  The  writer  would  thus  urge  the  following  method 
as  one  of  the  most  satisfactory  to  be  pursued : 

(1)  Examine  a  large  number  of  tubers  of  the  variety  selected  as 
the  foundation  stock  and  decide  on  the  most  desirable  shape  and 
type  of  tuber.  In  general  a  moderately  large  tuber,  which  is  oblong 
or  somewhat  cylindrical  in  shape  and  oblong  in  cross  section,  is 
considered  most  desirable.  A  spherical  tuber  if  sufficiently  large 
to  be  desirable  is  so  thick  that  in  cooking  the  outside  is  likely  to 
become  overdone  before  the  interior  is  properly  cooked.  A  tuber 
with  shallow  eyes,  netted  surface  and  white  color  is  also  usually 
preferred.  Probably  the  best-sized  potato  for  general  use  is  one 
weighing  seven  to  eight  ounces.     A  potato  of  this  size  does  not  have 


64  The  Potato 

to  be  cut  when  served,  as  a  single  tuber  is  about  the  right  size  to  an 
individual.  Again  this  sized  tuber  is  well  fitted  for  cooking  and  it  is 
small  enough  so  that  the  interior  will  cook  nearly  as  quickly  as  the 
exterior.  Probably  the  most  desirable  shape  is  when  the  tuber  has 
a  major  axis  or  length  of  three  and  one-half  inches  to  four  inches,  with 
a  width  of  possibly  three  to  three  and  one-fourth  inches,  and  a  thick- 
ness of  two  to  two  and  one-fourth  inches.  In  a  tuber  of  this  shape 
the  center  of  the  potato  at  any  point  is  only  about  one  inch  from  the 
exterior. 

(2)  When  the  ideal  character  and  size  have  been  determined, 
examine  a  large  number  of  tubers  and  pick  out  a  thousand  or  more 
having  this  size,  shape  and  general  character.  This  is  work  that 
can  be  done  in  the  late  fall  and  winter  when  there  is  no  rush  of  other 
farm  work,  and  time  should  be  taken  to  secure  a  considerable  number 
of  these  tubers  of  the  same  character.  These  are  to  be  used  for 
planting  the  selection  plot,  and  the  number  selected  should  correspond 
to  the  size  of  the  plot  which  it  is  desired  to  plant,  four  hills  being 
planted  with  each  tuber.  There  should  certainly  not  be  less  than  one 
thousand,  and  a  much  larger  number  is  more  desirable.  The  pro- 
spective breeder  should  remember  that  success  in  breeding  work  de- 
pends upon  selecting  the  one  individual  that  gives  the  very  highest 
yield  possible  under  the  conditions,  and  the  larger  the  number  of 
individuals  examined  the  more  likely  is  he  to  discover  the  one  produc- 
ing the  maximum  yield  which  will  give  a  valuable  new  strain.  There 
is  no  loss  in  growing  this  selection  plot  aside  from  the  greater  amount 
of  time  required  for  the  digging,  so  that  one  should  grow  a  consider- 
able number  of  plants. 

(3)  The  planting  should  be  arranged  in  such  a  way  as  to  secure 
a  test  of  the  productivity  of  each  tuber.  To  do  this  the  following 
method  may  be  recommended.  Cut  each  tuber  into  four  uniform 
sized  pieces,  making  each  cut  longitudinally  so  that  each  piece 
will  contain  an  equal  proportion  of  the  basal  end  and  the  apical  end 
of  the  tuber.  Plant  four  hills  with  each  tuber,  one  piece  in  the  hill. 
These  should  be  planted  consecutively  in  each  row  beginning  at  one 
end,  so  that  starting  at  that  end  the  first  foiu-  hills  will  be  from  one 
tuber,  the  second  foiu-  from  another  and  so  on  throughout  the 
length  of  the  row.  The  object  in  planting  this  way  is  that  four  hills 
can  be  dug  together  and  the  total  product  weighed  to  obtain  a  meas- 
ure of  the  productivity  of  the  seed  tuber  planted.  Probably  the 
best  way  to  plant  these  is  to  drop  the  selected  tubers  one  to  each 


Potato  Breeding  65 

four  liills  and  then  go  over  the  row  and  cut  each  tuber  and  plant 
its  quota  of  four  hills.  The  hills  in  the  row  should  be  planted  some- 
what farther  apart  than  in  ordinary  planting,  probably  20  to  24 
inches.  If  this  is  not  done,  a  somewhat  greater  distance  than  ordinary 
should  be  left  between  each  two  four-hill  tuber-units.  The  writer 
would  advise  that  one  hill  be  left  unplanted  between  each  two  four- 
hill  units.  It  would  doubtless  be  convenient  and  desirable  to  have 
the  plants  in  rows  both  ways  to  facilitate  digging.  For  this  selec- 
tion-plot of  potatoes,  choose  a  field  of  moderately  good  fertility  and 
as  uniform  throughout  in  soil  as  it  is  possible  to  obtain. 

(4)  Manm"e  and  cultivate  the  plot  of  potatoes  grown  for  selec- 
tion just  the  same  as  you  do  your  ordinary  crop. 

How  to  make  the  selection  of  potatoes — field  examination.  —  A 
careful  examination  of  the  selection  field  should  be  made  as  the 
vines  begin  to  matiu-e  and  while  they  are  yet  green.  This  examina- 
tion should  include  observations  on  diseases  and  vigor  of  the  tops. 
If  there  are  any  marked  differences  apparent  between  the  different 
four-hill  units,  those  with  the  best-appearing,  most  healthy  tops 
should  be  marked  by  small  stakes  which  can  be  stuck  in  the  ground 
beside  the  hills.  This  field  examination,  while  important  in  careful 
work,  probably  could  be  omitted  without  very  great  loss,  as  after  all 
the  yield  is  tlie  primary  character. 

Digging  the  selection  field.  —  The  digging  of  the  field  grown  for 
selection  purposes  requires  considerable  care,  and  here  hard  work  is 
necessary.  Dig  each  four-hill  unit  grown  from  the  same  tuber  sei)a- 
rately,  being  careful  to  get  all  of  the  product,  and  avoid  cutting  or 
injm-ing  the  tubers  if  possible.  Carefully  place  the  product  of  each 
foiu"-hill  tuber-unit  together  at  one  side  of  the  row,  and  if  it  is  a  tuber- 
unit  marked  with  a  stake  in  the  field  examination,  keep  the  stake 
with  the  product  of  the  unit.  A  good  way  to  dig  in  order  to  avoid 
getting  the  hills  of  different  tuber-units  mixed  is  to  dig  across  the 
field,  in  a  direction  at  right  angles  to  the  direction  the  rows  were 
planted.  First  dig  the  four  hills  of  the  first  tuber  planted  in  the  first 
row,  then  the  four  from  the  first  tuber  in  the  second  row,  then  the 
same  in  the  third  row,  fourth  row,  etc.,  tlirough  the  field.  Next 
dig  the  foiu"  hills  from  the  second  tuber  planted  in  the  first  row,  then 
the  four  from  the  second  tuber  in  the  second  row,  etc.  By  this 
method  of  digging,  especially  if  the  hills  are  rowed  both  wa^'s,  there 
will  be  little  danger  of  mixing  the  product  of  the  four-hill  units. 

Making  the  selections.  —  The  problem  after  digging  is  to  select 


66  The  Potato 

fifty  to  one  hundred  of  the  best  tuber-units,  —  best,  that  is,  in  jneld, 
uniformity  of  product,  color,  shape,  etc.  After  the  potatoes  are  dug 
and  the  product  of  each  tuber-unit  is  laid  out  separately,  the  real 
work  of  selection  begins.  The  following  are  the  important  steps  in 
this  process : 

(1)  Go  over  the  field  and  study  the  tuber-units  in  a  gross  way 
until  you  have  well  in  mind  the  variations  in  yield  and  the  gen- 
eral uniformity  of  the  tubers  in  the  various  tuber-units.  Re- 
member that  the  total  yield  is  not  the  only  important  character. 
What  one  wants  is  to  discover  those  tuber-units  which  have  the 
largest  yield  of  good  merchantable  potatoes  of  the  best  shape  and 
appearance.  Size  up  the  field  as  a  whole  with  reference  to  these 
characters. 

(2)  Go  over  each  row  carefully  and  throw  out  all  of  those  tuber- 
units  which  can  be  clearly  seen  to  be  inferior ;  these  may  be  thrown 
together  and  placed  with  the  general  crop  of  potatoes.  For  the 
interest  of  the  grower,  however,  it  would  be  well  to  weigh  the  prod- 
uct from  some  of  the  light-yielding  tuber-units  and  preserve  the 
figures  for  the  sake  of  showing  the  extent  of  variations  occurring. 
By  this  first  discarding  process  the  number  of  tuber-units  will  proba- 
bly have  been  reduced  to  two  or  three  hundred.  It  is  very  prob- 
able that  in  some  cases  one  or  more  of  the  hills  of  a  four-hill  tuber- 
unit  will  not  grow.  In  such  cases  the  tuber-unit  will  have  to  be 
judged  in  proportion  to  the  number  of  hills  actually  grown. 

(3)  Now  provide  yourself  with  scales  of  some  handy  pattern 
like  the  ordinary  counter  scales  used  by  grocers,  with  which  the 
product  of  each  tuber-unit  can  be  easily  and  quickly  weighed.  A 
satisfactory  scale  should  weigh  accurately  to  at  least  a  half  ounce. 
Weigh  the  product  of  the  remaining  tuber-units,  examine  the  tubers 
more  carefully  as  to  their  character  and  uniformity  of  size  in  the 
tuber-unit  and  select  about  fifty  of  the  best  units.  These  fifty 
units  should  naturally  be  from  those  marked  as  having  good  healthy 
vines  in  the  first  examination  before  digging,  unless  all  of  the  vines 
at  that  time  were  in  fairly  good  condition.  In  making  these  final 
selections,  if  some  hills  in  the  tuber-unit  are  missing,  the  comparative 
yield  can  be  easily  calculated.  If  one  hill  is  missing,  a  comparative 
yield  for  four  hills  is  obtained  by  increasing  the  weight  from  the  three 
hills  by  one-third.  If  two  hills  are  missing,  a  comparative  yield  for 
four  hills  would  be  double  that  obtained  from  the  two  hills.  If  more 
than  two  hills  are  missing,  discard  the  unit  entirely. 


Potato  Breeding  67 

The  product  of  the  tuber-units  selected  should  then  be  placed  in 
paper  bags,  the  product  of  one  tuber-unit  only  being  placed  in  a  bag. 
A  good  bag  for  the  purpose  is  the  12  or  16  pound  manila  paper  bag 
used  by  grocers.  The  12-pound  paper  bags  of  good  quality  should 
cost  only  about  40  cents  per  hundred.  If  the  12-pound  paper  bag 
is  too  small,  use  a  16-pound  bag.  In  your  notebook  record  under 
the  number  of  each  tuber-unit,  the  number  of  large,  medium-sized, 
and  small  tubers  and  the  total  weight  of  the  product.  The  bags 
containing  the  seed  should  then  be  placed  in  suitable  storage  where 
they  will  not  be  torn  or  the  tubers  mixed.  The  tubers  from  the 
best  discarded  tuber-units  should  be  retained  to  plant  the  general 
crop  the  next  year. 

If  at  digging  time  the  grower  is  crowded  with  work  and  wishes 
to  save  time,  the  two  or  three  hundred  tuber-units  retained  after  the 
first  gross  selection  (see  paragraph  2  above)  could  be  placed  in  paper 
bags  and  the  more  careful  examination  and  weighing  of  the  product 
delayed  until  some  convenient  time  during  the  winter  when  the  final 
selection  could  be  made. 

Selecting  seed  for  the  second  year's  planting.  —  Some  time  during 
the  winter  or  at  any  convenient  period  before  planting  time  care- 
fully examine  the  product  of  each  select  tuber-unit  and  pick  out  the 
ten  best  tubers  of  each  as  judged  by  the  ideal  standard  of  a  good  tuber 
which  has  been  taken  as  the  type  of  the  selection.  The  ten  best  of 
each  retain  in  the  numbered  sacks  for  planting  and  discard  the  re- 
maining tubers. 

Second  year's  planting.  —  In  the  further  handling  of  the  selec- 
tions made  the  first  year  the  planting  the  second  year  must  be  ar- 
ranged in  order  to  test  the  productive  power  of  each  of  the  fifty 
select  tuber-units.  Plant  each  tuber-unit  in  a  row  by  itself  by  the 
same  method  used  in  planting  the  first  year's  crop  (see  p.  64).  That 
is,  plant  four  hills  with  each  tuber,  cutting  the  tuber  longitudinally 
into  four  equal-sized  quarters,  making  each  cut  from  base  to  apex 
of  the  tuber.  As  ten  select  tubers  were  retained  from  each  tuber- 
unit  this  will  make  forty  hills  per  row,  and  if  fifty  tuber-units  were 
selected,  there  will  be  500  tubers  to  plant,  which  will  make  a  total 
of  2000  hills  in  the  breeding-plot.  The  land  used  for  this  breeding- 
plot  should  be  carefully  chosen  for  uniformity,  as  variations  in  the 
land  will  modify  the  comparative  yield  and  are  likely  to  render  the 
results  untrustworthy.  Number  each  row  of  forty  hills  with  the 
number  given  the  tuber-unit  of  the  preceding  year.     It  is  desirable 


68  The  Potato 

for  comparison  to  plant  about  every  tenth  row  with  unselected 
seed  of  the  same  variety,  cut  and  planted  in  the  same  way,  but 
without  reference  to  keeping  each  tuber  separate.  The  production 
of  these  check-rows  will  show  whether  progress  is  being  made  in  the 
selection. 

Cultivate  the  breeding  plot  and  treat  it  otherwise  just  as  an  ordi- 
nary crop  is  treated. 

Making  the  second  year's  selection.  —  Wlien  the  breeding  plot 
ncars  maturity,  the  individuals  should  be  examined  and  either  the 
best  and  healthiest  vines  marked  or,  if  easier,  the  diseased  vines 
showing  weakness  marked,  so  that  they  can  be  discarded  later. 
Then  dig  each  tuber-unit  as  in  the  preceding  year,  placing  the  tubers 
from  each  four-hills  together  at  the  side  of  the  row.  Each  unit  should 
then  be  weighed  and  the  number  of  large,  medium  and  small  sized 
tubers  recorded.  This  will  enable  the  breeder  to  determine  which  of 
the  original  fifty  tuber-units  selected  in  the  first  year  has  given  the 
largest  average  yield  in  the  ten  tuber-units  or  forty-hill  test,  and 
this  is  the  primary  test  of  the  value  of  the  original  selection.  Follow- 
ing the  same  method  as  used  the  first  year,  select  from  the  breeding- 
plot  the  fifty  best  tuber-units,  and  preserve  the  tubers  of  each  unit 
separately  in  a  paper  bag.  The  majority  of  the  selection  in  this 
year  should  naturally  be  made  from  those  rows  which  have  given 
the  highest  yield.  Number  the  tuber-units  selected  in  this  second 
generation  1-1,  1-2,  1-3,  etc.,  and  2-1,2-2,  etc.  In  such  hyphenated 
numbers  the  first  figure  refers  to  the  number  of  the  tuber-unit  se- 
lected the  first  year,  and  the  second  number,  that  following  the 
hyphen,  refers  to  the  number  of  tuber-units  elected  from  this  prog- 
eny the  second  year.  Thus  in  the  case  of  2-2,  the  first  2  indicates 
that  it  was  the  second  tuber-unit  selected  in  the  second  year  from 
progeny  of  unit  No.  2  of  the  first  year's  crop.  In  the  third  year  the 
numbers  can  be  extended  by  the  same  principle,  the  tuber-units 
selected  from  progeny  2-2  in  the  third  year  being  numbered  2-2-1, 
2-2-2,  2-2-3,  etc.  These  numbers  can  be  placed  on  the  bags  and 
notes  on  weight  of  yield,  number  of  tubers  per  unit,  etc.,  recorded 
under  the  same  number. 

All  of  the  good  tubers  from  the  remaining  tuber-units  of  the 
breeding-[)lot  not  selected  should  be  retained  for  planting  a  multi- 
plication-plot the  third  year,  which  should  furnish  sufficient  seed  for 
planting  the  general  crop  for  the  fourth  year. 

At  some  convenient  period  before  planting  time,  as  in  the  pre- 


Potato  Breeding  69 

ceding  year,  go  over  the  product  of  each  select  tiiber-unit  and  pick 
out  the  ten  best  tubers  of  each  for  the  next  year's  planting. 

Continuing  selections  in  third  year.  —  In  the  third  year,  the  fifty 
selections  of  heavy  yielding  tuber-units  should  be  planted  by  the 
same  method  used  the  second  year,  at  least  forty  hills  of  each  selec- 
tion being  planted.  The  row  from  each  unit  should  be  plainly  la- 
beled or  otherwise  marked  to  avoid  mixing  the  pedigree.  Treat  this 
breeding-plot  as  described  for  the  breeding-plot  in  the  second  year, 
weigh  up  the  product  of  each  four-hill  tuber-unit  in  the  same  way  to 
determine  which  unit  of  the  second  year's  selection  has  transmitted 
in  greatest  degree  the  tendency  to  yield  heavily.  Finally,  select 
again  the  best  fifty  tuber-units  to  continue  the  breeding,  and  retain 
the  good  tubers  of  discarded  units  to  plant  a  multiplication  in  the 
fourth  year. 

In  the  third  year,  a  multiplication-plot  should  be  planted  with  the 
good  tubers  from  the  discarded  tuber-units  of  the  breeding  plot  of 
the  second  year.  In  planting  this  plot  the  grower  can  use  any 
method  of  cutting  and  planting  the  tubers  which  he  thinks  most 
desirable.  This  plot  should  give  enough  seed  to  plant  a  fairly  large 
plot  in  the  fourth  year. 

Continuing  selections  in  fourth  and  succeeding  years.  —  In  the 
fourth  and  succeeding  years  the  selection  should  be  conducted  by 
the  same  plan  as  outlined  above.  When  this  system  is  well  under 
way,  it  will  be  seen  that  each  year  the  breeder  is  growing  a  small 
breeding-plot,  a  large  multiplication-plot  for  seed  and  a  general 
crop. 

Further  considerations.  —  As  the  selection  progresses  many  of  the 
strains  from  the  original  fifty  tuber-units  will  be  entirely  discarded. 
The  breeder  must  be  continually  watching  for  the  appearance  of  a 
heavy  yielding  strain,  and  if  such  a  strain  is  discovered,  all  of  the 
further  selections  should  be  made  from  this  strain. 

In  advocating  the  selection  of  but  fifty  tuber-units  and  the 
planting  of  ten  tubers  only  from  each  select  unit  the  writer  has 
had  in  mind  the  reduction  of  the  work  to  a  comparatively  simple 
plan  which  would  be  better  to  handle  larger  numbers  if  the  grower 
is  so  situated  that  he  can  take  the  time  for  it.  It  is,  however,  better 
to  use  comparatively  small  numbers  carefully  than  to  attempt  to. 
handle  large  munbers  and  find  the  work  too  extensive. 


70  The  Potato 

Another  method  of  selection  has  been  suggested  which 
is  simpler  than  Webber's  method,  probably  not  as  satis- 
factory, but  which  has  been  found  very  useful  by  many 
growers.  It  consists  of  planting,  growing  and  digging 
the  tubers  the  first  year  as  previously  suggested,  but  in- 
stead of  weighing  the  hills  and  keeping  them  separate  for 
further  tests,  they  are  chosen  by  means  of  counting  in- 
stead of  weighing.  If  the  season  has  been  an  average 
one,  the  hills  which  have  six  or  more  good  tubers  are 
saved  for  future  planting.  Perhaps  it  may  be  necessary 
to  use  five  as  a  standard  of  selection  or  even  seven  may  be 
used  if  the  crop  is  good.  There  is  no  attempt  at  pedi- 
gree breeding  by  keeping  the  different  strains  separate. 
All  hills  meeting  the  established  standard  are  thrown 
together  and  saved  for  seed.  The  next  year  these  are 
planted  and  grown  like  the  rest  of  the  field.  In  the  fall 
they  are  dug  by  hand  and  again  the  best  hills  by  count 
are  saved  for  seed.  This  method  will  gradually  elimin- 
ate the  poor  strains  and  raise  the  average  yield  of  the 
crop  very  rapidly. 

Spillman  says :  "  A  potato  grower  in  Michigan  some 
years  ago  began  the  practice  of  digging  by  hand  enough 
potatoes  for  seed  and  saving  only  those  hills  that  had  six 
or  more  merchantable  tubers  and  no  small  tubers.  When 
he  first  began  this  practice,  only  sixteen  hills  out  of  each 
hundred  dug  came  up  to  his  standard,  but  after  he  had 
continued  this  practice  for  five  years  the  number  of  such 
hills  had  risen  to  seventy  in  a  hundred." 

Another  similar  instance  is  found  in  some  unpublished 
results  secured  by  Dodge  of  the  office  of  Farm  Man- 
agement, who  for  several  years  has  been  teaching  some 
New  England  potato-growers  how  to  select  seed  potatoes. 
The  method  adopted  is  to  save  for  seed  those  hills  that 


Potato  Breeding  71 

produce  six  or  more  merchantable  tubers.  This  experi- 
ment has  extended  over  three  years.  The  first  year, 
from  7  per  cent  to  8  per  cent  of  hills  were  found  that  met 
the  requirements ;  the  second  year  from  17  per  cent  to 
20  per  cent.  This  season  the  number  of  hills  which  have 
produced  six  or  more  merchantable  tubers  has  risen  to 
24  per  cent  to  27  per  cent. 

Whenever  pure  lines  or  strains  or  varieties  of  potatoes 
are  compared,  every  effort  should  be  made  to  eliminate 
soil  differences  or  other  factors  of  environment,  so  that  a 
direct  test  of  the  heredity  only  can  be  made.  Potatoes 
are  so  easily  influenced  by  environment  that  real  heredi- 
tary differences  are  often  covered  up.  Absolute  uni- 
formity in  time  of  planting,  methods  of  culture,  spraying 
and  so  forth  are  essential.  The  seed  pieces  should  be  as 
nearly  the  same  weight  as  possible.  Arthur  says,  "  What- 
ever increases  rate  of  growth  at  the  beginning,  increases 
yield." 

If  tuber-units  are  being  compared,  they  should  be 
planted  in  duplicate  or  preferably  in  triplicate  in  differ- 
ent parts  of  the  field  and  their  production  averaged. 

If  single  high-producing  hills  are  saved  for  the  next 
year's  planting,  one  should  make  sure  that  they  did  not 
come  from  some  highly  fertilized  part  of  the  field.  Pref- 
erably they  should  be  chosen  from  the  poorer  parts  of  the 
field  when  their  production  may  be  high  in  spite  of  their 
environment,  the  real  test  of  heredity. 

Zavitz,  of  the  Ontario  Experiment  Station,  selected 
the  best  hills  of  seven  varieties  of  potatoes  for  a  period 
of  sixteen  years.  During  the  first  four-year  period 
the  average  yield  was  120  bushels.  During  the  three 
succeeding  periods  of  four  years  each,  as  a  result  of 
selection,  the  average  yields  were  increased  to  216,  218 


72 


The  Potato 


and  249  bushels.  Within  the  sixteen-year  period,  the 
methods  of  culture  were  kept  practically  the  same 
and  the  result  is,  therefore,  attributed  to  the  result  of 
selection. 

Waid  has  conducted  at  the  Ohio  Experiment  Station 
a  series  of  experiments  for  the  purpose  of  securing  data 
to  throw  more  light  on  the  question  of  the  value  of  hill 
selection  in  potatoes.  In  this  work,  starting  with  the 
same  original  lot  of  tubers,  three  strains  were  grown 
as  follows :  (1)  seed  from  high-yielding  hills ;  (2)  seed 
from  low-yielding  hills ;  (3)  unselected  seed.  The  fol- 
lowing table  gives  the  summary  of  the  results  that  were 
obtained  from  high-yielding  hills  and  from  low-yielding 
hills: 

Table  XI.  —  Summary  of  Results  from  Use  of  Seed  Po- 
tatoes FROM  High-yielding  Hills  and  from  Low-yield- 
ing Hills.     (Variety,  Carman  No.  3) 


Source  of  Seed 

Yield  of  100  Hills 

Number  op  Tubers  in 
100  Hills 

Total 
1904 

Total 
1905 

Total 
1906 

Average 
1904-5-6 

Total 
1904 

Total 
1905 

Total 
1906 

Average 
1904-5-6 

High-yielding  hills  . 
Cheek  rows     .     .     . 
Low-yielding  hills    . 

Lhs. 

125 
115 
84 

Lbs. 

173 

136 

75 

Lbs. 

116 
79 
61 

Lhs. 

138 

110 

73 

781 
713 
566 

865 
630 
546 

676 
479 
364 

774 

607 
492 

Running  out  of  varieties 

Potatoes  are  grown  in  many  parts  of  the  world  where 
the  climate  and  soil  are  very  different  from  that  of  their 
native  home.  Also  all  of  our  varieties  which  have  been 
developed  as  a  result  of  breeding  give  yields  far  in  excess 


Potato  Breeding  73 

of  the  wild  forms.  The  stress  of  uncongenial  environment 
and  hirge  production  of  tubers  causes  most  varieties  to  lose 
this  abnormal  (from  the  standpoint  of  the  plant)  produc- 
ing power  and  to  decline  unless  selection  is  constantly- 
practiced.  Disease  may  be  partially  responsible  for  this 
degeneration. 

Running  out  of  varieties  is  often  caused  by  repeated 
planting  of  culls  and  poorer  specimens  while  the  best  are 
sent  to  market. 

Newman  ^  says,  that  in  vSweden  there  is  a  potato  known 
as  the  Dala,  which  is  said  to  have  been  introduced  about 
150  years  ago  and  is  still  one  of  their  best  sorts.  The 
opinion  held  at  Svalof  is  that  there  is  no  period  of  old  age 
in  a  variety  of  potatoes ;  that  where  suitable  sorts  are 
used,  and  where  suitable  tubers  of  these  sorts  are  used  for 
seed  purposes  each  year,  the  planting  of  the  variety  may 
be  maintained  indefinitely  under  all  favorable  conditions 
of  soil  and  climate.  The  main  considerations  are  mainte- 
nance of  vigor  and  control  of  disease,  and  this  implies 
careful  selection  of  seed  tubers,  careful  cultivation  and 
spraying  and  rotation  of  crops.  Special  emphasis  is 
laid  upon  the  latter  point. 

Orton  sa}^s :  "  The  same  system  of  seed  selection  and 
treatment  and  crop  rotation  that  will  free  the  potato 
fields  of  wilt,  leaf-roll,  and  curly-dwarf  will  at  the  same 
time  not  only  bring  under  control  the  blackleg  and  some 
other  diseases  but  will  insure  the  maintenance  of  the 
strains  cultivated  in  their  most  vigorous  and  productive 
condition  and  be  free  from  objectionable  mixtures  with 
other  varieties." 

The  following  statement  from  Fruwirth  is  representa- 

•  "  Plant  Breeding  in  Scandinavia."  Canadian  Seed  Growers  Associa- 
tion, Ottawa  (1912). 


74  The  Potato 

tive  of  the  opinion  held  by  most  of  the  European  experi- 
menters. "And  the  real  degeneration,  an  ageing  of  a 
variety,  which  has  been  under  uniformly  favorable  condi- 
tions and  of  which  good  seed  is  used  has  not  been  pro\'ed 
and  is  improbable." 

Varieties  seem  to  differ  in  their  staying  qualities. 
Some  have  held  up  for  50  to  60  years,  while  others  have 
passed  out  quickly.  The  old  Peachblow  variety  which 
was  widely  grown  forty  years  ago  has  largely  run  out 
now  except  in  certain  localities  like  the  Carbondale  region, 
where  it  has  been  given  careful  selection  and  is  better 
to-day  than  ever  before. 

Another  reason  ascribed  is  that  long-continued  bud 
propagation  results  in  an  inner  physiological  weakening. 
It  is  difficult  to  see,  however,  how  prolonged  asexual 
propagation  affects  stocks  injuriously. 

What  appears  to  be  the  running  out  of  a  variety  may, 
in  some  instances,  be  due  to  a  change  in  market  demands 
and  the  varieties  disappearing  which  do  not  meet  these 
demands.  For  example,  the  old  long  Burbank  has 
given  place  to  the  more  round  varieties  such  as  the  Rural, 
and  the  Blue  Victor  has  been  replaced  by  white  varieties 
and  has  now  practically  gone  out  of  existence.  Fru- 
wirth  believes  that  a  lack  of  adaptation  to  local  condi- 
tions results  in  a  degeneration  of  certain  varieties.  Poor 
attention  to  the  selection  of  seed  tubers  is  also  suggested 
as  a  cause  of  deterioration.  Fruwirth  summarizes  the 
opinions  of  a  number  of  German  experimenters  in  sup- 
port of  these  two  views. 

East  points  out  that  perhaps  the  potato  requires 
frequent  crossing  to  keep  up  the  vigor,  and  that  possibly 
continual  propagation  by  asexual  methods  causes  a  loss 
of  heterozygosis. 


Potato  Breeding  lb 

Certain  plant  characters  are  often  associated  together. 
In  breeding  practice  a  knowledge  of  these  associations 
is  often  valuable.  If  easily  observable  physical  char- 
acters, such  as  color  of  flower  or  texture  of  skin,  are  asso- 
ciated with  chemical  composition,  which  is  less  easily 
detected,  the  appearance  of  the  former  is  a  valuable 
index  to  the  existence  of  the  latter.  It  has  been  often 
observed  that  there  is  a  certain  shade  of  green  in  the 
leaves  which  is  correlated  with  vigor  and  high  produc- 
tivity. If  the  leaves  are  too  light  green,  few  tubers  will 
be  produced,  or  if  too  dark,  the  yield  is  again  small  or  a 
large  number  of  small  tubers  will  be  found,  due  to  late 
maturity  or  possibly  to  disease.  Correlations  are  es- 
pecially valuable  when  they  enable  one  to  select  out  good 
plants  in  a  young  stage,  or  when  they  save  the  trouble  of 
making  elaborate  chemical  analysis.  Only  a  few  defi- 
nite correlations  have  been  discovered  in  the  potato. 
East  reports  nearly  all  of  these  in  Illinois  Bulletin  127, 

There  appears  to  be  a  positive  correlation  between 
yield  and  the  following  :  flat  shape  of  tuber,  number  of 
stalks  to  the  plant  and  length  of  the  growing  season. 
With  a  heavy  setting  of  seed  berries,  we  may  usually 
expect  a  light  production  of  tubers.  No  correlation  has 
yet  been  found  between  color  of  the  tuber  and  yield. 

Fischer  of  Germany  (reported  by  East)  says  that  round- 
flat  tubers  tend  to  produce  plants  which  are  rather  com- 
pact in  habit.  Cylindrical  tubers  produce  large,  scraggly 
plants. 

Round-flat  tubers  are  richest  in  starch.  Quality  is 
said  to  improve  directly  with  an  increase  in  starch  con- 
tent up  to  a  certain  point.  An  excessive  amount  of 
starch  causes  the  tuber  to  be  coarse  and  woody.  A 
netted  skin  is  usually  associated  with  high  quality. 


76  TJw  Potato 

No  correlation  has  been  discovered  between  color  of 
tubers  and  color  in  the  stems  and  flowers. 

In  certain  varieties  there  seems  to  be  a  coupling  of 
characters  and  what  appears  to  be  a  close  correlation. 
This  same  association,  however,  may  not  hold  for  any 
other  variety.  As  East  points  out,  we  ought  to  have  a 
good  understanding  of  the  life  history  of  different  varie- 
ties before  we  draw  definite  conclusions  as  to  the  correla- 
tion of  characters. 

Appearance  of  bud  sports 

Occasionally,  a  single  bud,  or  group  of  buds,  on  a  tuber 
will  give  rise  to  a  plant  distinctly  unlike  any  others  of 
the  variety.  This  is  known  as  bud-sporting.  Just 
what  causes  this  unusual  behavior  we  can  only  speculate 
upon.     No  definite  cause  is  known. 

Darwin  reports  three  cases  of  bud  sporting.  A  tuber  of 
the  purple  variety  "Forty-fold"  had  a  single  eye  that  was 
white.  This  when  planted  gave  rise  to  a  white  variety. 
The  same  purple  variety  in  another  instance  produced  a 
white  tuber  which  bred  true.  The  white  variety  "  Kemp  " 
sported  to  give  the  red  "Taylor's  Forty-fold." 

Fruwirth  reports  a  case  where  a  yellow  tuber  gave 
rise  to  a  violet-skinned  form.  Examples  of  this  sort 
are  rather  numerous. 

Such  bud  sporting  is  not  limited  to  characters  of  the 
tuber.  Many  believe  that  habit  of  vine,  vigor,  produc- 
tiveness and  other  characters  may  be  affected  by  sporting 
of  the  tuber  buds. 

By  carefully  examining  the  hills  of  the  breeding  plot 
at  digging  time,  any  valuable  bud  sports  can  be  selected 
out  for  further  propagation. 


Potato  Breeding  77 

Improvement  by  hyhridization 

It  is  hardly  advisable  for  the  practical  potato-grower 
to  attempt  an  extensive  improvement  of  his  crop  by 
hybridization.  While  the  method  has  yielded  good 
results  in  some  cases,  there  are  many  difficulties  in  the 
way  and  the  results  are  very  uncertain.  The  major 
portion  of  a  farmer's  potato  breeding  plot  should  be 
given  over  to  tuber-unit  tests.  If  the  grower  feels  that 
he  can  spare  the  time  and  is  willing  to  risk  a  failure  in 
his  enterprise,  it  would  be  of  interest  and  possibly  of 
profit  to  attempt  a  few  crosses  between  his  better  strains. 
Otherwise  this  method  should  be  left  to  the  experiment 
station  worker,  who  has  the  time  to  make  the  large 
number  of  manipulations  necessary,  and  who  can  devote 
large  areas  to  the  growing  of  the  seedlings. 

Plants  are  hybridized  primarily  to  increase  their  varia- 
bility and  to  furnish  more  material  on  which  to  practice 
selection.  In  the  light  of  modern  mendelian  studies, 
we  have  come  to  look  upon  hybrids  as  recombinations 
of  characters  present  in  the  parents.  Care  should  be 
exercised  to  choose  parents  having  as  many  desirable 
characters  as  possible.  Subsequent  selections  should 
preserve  those  plants  which  combine  the  largest  number 
of  desirable  qualities  from  both  parents.  Hybridiza- 
tion usually  increases  vigor  and  is  often  useful  in  restor- 
ing this  characteristic  in  weakened  strains. 

There  are  certain  conditions  which  make  the  successful 
hybridization  of  potatoes  very  difficult.  In  the  first 
place,  there  is  a  strong  tendency  in  most  varieties  not  to 
set  seed.  In  such  varieties,  the  flowers  drop  off  shortly 
after  pollination.  This  necessitates  making  a  great 
many  pollinations  with  the  hope  that  a  few  plants  will 


78  The  Potato 

set  seed.  Salaman  ^  estimates  that  only  5  per  cent  of 
his  crosses  set  seed.  East  -  found  it  difficult  to  get  a 
good  setting  of  seed  in  very  dry  seasons. 

In  some  cases,  persistent  attempts  have  finally  resulted 
in  a  successful  cross  where  at  first  it  seemed  impossible. 
A  second  drawback  is  the  scarcity  of  pollen.  Many 
varieties  produce  little  or  no  pollen  and  have  to  be  crossed 
if  we  are  to  get  sexually  produced  seed  from  them.  Also, 
some  plants  produce  yellow  pollen  which  is  sterile  and 
does  not  function.     Other  varieties  rarely,  if  ever,  flower. 

Most  varieties  of  potatoes  are  already  hybrid  and 
when  seed  from  them  is  sown,  the  type  breaks  up  into 
many  elementary  forms,  most  of  which  are  of  no  value 
to  the  grower.  This  adds  another  difficulty  to  those 
mentioned  above.  Each  variety  which  is  crossed  trans- 
mits a  number  of  undesirable,  latent  characters  which 
come  out  in  the  hybrids.  Often  the  seedlings  from  a 
cross  will  show  so  many  of  the  traits  of  the  wild  potato 
that  none  of  them  is  worthy  of  further  attention.  Se- 
curing a  valuable  new  variety  from  a  cross  seems  in  this 
case  to  be  largely  a  matter  of  chance.  There  is  an  ele- 
ment of  uncertainty  in  the  work,  which  is  not  encoun- 
tered with  most  crops. 

The  potato  flower  consists  of  a  rotate  corolla  of  white, 
lilac  or  purple  petals,  five  green  sepals,  five  anthers  and 
a  single  pistil.  The  style  projects  up  through  the  "cone" 
formed  by  the  closely  adhering  anthers.  The  anthers 
open  at  the  tips  and  give  out  a  small  amount  of  pollen. 
In  the  day  time,  the  flower  is  in  an  erect  position,  and  it  is 
impossible  for  pollination  to  take  place.  At  night,  how- 
ever, the  flower  bends  over  and  some  of  the  pollen  can  fall 

1  Journ.  Gcii.,  Vol.  1,  pp.  7-46. 

2  Illinois  Bui.  127. 


Potato  Breeding  79 

down  on  to  the  stigma.  The  flowers  open  in  the  morn- 
ing and  close  late  in  the  afternoon.  Fruwirth  says  that 
potato  flowers  usually  give  off  pollen  the  second  day 
after  opening  and  wilt  the  third  or  fourth  day.  The 
period  of  flowering  for  a  single  plant  is  between  28  and 
33  days.  It  seems  to  be  a  general  opinion  that  the  potato 
flowers  are  only  rarely  visited  by  insects,  and  that  wind, 
also,  plays  little  part  in  the  pollination  of  the  blossoms. 

The  first  thing  to  be  done  in  hybridizing  plants  is  to 
decide  on  a  definite  ideal.  We  then  choose  our  parent 
plants  with  reference  to  this  imaginary  type,  trying  to 
obtain  plants  which  have  as  many  as  possible  of  the 
qualities  sought  in  the  new  form. 

Generally  speaking,  it  makes  no  difference  which 
variety  we  use  as  male  and  which  as  female  parent.  A 
great  deal  will  depend  on  the  nature  of  the  varieties 
themselves.  Obviously,  we  must  pick  for  male  parent  a 
variety  which  bears  at  least  a  moderate  amount  of  pollen. 

It  is  well  to  keep  in  mind  a  few  general  principles  of 
hybridization  as  we  proceed.  First,  the  plant  to  be 
used  as  female  parent  should  be  emasculated  to  prevent 
its  setting  seed  by  its  own  pollen.  This  must  be  done 
before  the  anthers  have  matured.  Secondly,  it  is  safest  to 
bag  flowers  to  be  used  in  crosses,  to  prevent  the  entrance 
of  foreign  pollen.  And  lastly,  the  pollen  should  be  applied 
to  the  stigma  when  that  part  is  in  a  receptive  condition. 

Mature  potato  flowers  should  be  examined  so  that  one 
may  become  familiar  with  their  structure.  One  should 
learn  when  the  anthers  are  mature  and  when  the  stigma 
is  ready  for  pollination.  Just  before  the  bud  unfolds 
the  flower  to  be  used  as  a  seed  parent  is  opened  with  a 
pair  of  fine-pointed  forceps.  All  the  stamens  are  care- 
fully removed,  being  careful  not  to  break  any  or  to  leave 


80  The  Potato 

parts  of  them  in  the  flower.  This  must  be  done  before 
the  pollen  is  mature.  All  near-by  flowers  should  be  re- 
moved and  buds  other  than  those  emasculated.  As  the 
flowers  invariably  fall  off  when  bagged,  this  precaution 
must  be  omitted.  The  potato  is  not  frequently  cross 
pollinated  (Salaman)  and  the  danger  of  contamination 
is  slight.  It  is  necessary  to  tag  the  flowers  thus  treated 
in  order  to  know  later  on  when  to  pollinate  them.  The 
tag  should  bear  the  date  of  emasculation  and  other  facts 
of  which  the  hybridizer  wishes  to  keep  a  record.  A 
day  or  two  after  emasculation,  the  pistils  of  the  emascu- 
lated flowers  should  be  examined.  When  the  tips  have 
turned  a  slightly  darker  color  and  look  sticky,  they  are 
ready  to  receive  the  pollen. 

As  the  pollen  is  usually  borne  in  small  quantities,  it 
is  well  to  open  the  anthers  with  the  point  of  the  forceps 
and  scrape  it  out  on  to  the  thumb  nail  or  on  to  a  watch 
crystal.  A  thin  film  of  pollen  on  a  watch  crystal  will 
pollinate  a  number  of  blossoms.  It  is  customary  to  make 
two  or  three  pollinations  on  the  same  flower  in  order  to 
catch  it  in  a  perfectly  receptive  condition.  Once  the 
ovary  starts  to  swell,  there  is  little  likelihood  of  the 
flower  falling  off.  The  berry  should  be  picked  off  when 
fairly  dry  and  before  it  falls  off  and  rolls  away.  A  record 
should  be  kept  of  the  dates  of  emasculation  and  polli- 
nation, and  of  the  parents  concerned  in  each  cross. 

Potato  seed  should  be  washed  free  of  pulp  and  care- 
fully dried,  in  the  fall.  If  left  in  the  pod,  it  is  likely  to 
decay.  Each  pod  normally  bears  from  one  to  three  hun- 
dred seeds.  The  seed  should  be  planted  indoors  in  March 
or  April.  The  seedlings  are  potted  up  when  they  need 
moving,  and  set  out  in  the  field  in  June.  They  should 
be  planted  about  two  feet  apart. 


Potato  Breeding  81 

Shoots  are  sent  down  into  the  ground  from  the  axils 
of  the  first  leaves,  and  it  is  on  these  that  the  tubers  are 
borne.  As  a  rule,  the  tubers  for  the  first  year  vary  in  size 
from  that  of  a  marble  to  that  of  a  hen's  egg.  In  unusual 
cases  single  tubers  have  been  obtained  the  first  year 
which  weighed  over  a  pound.  Wilson  ^  reports  a  total 
yield  of  6  pounds  3  ounces  for  a  single  seedling  plant. 

It  is  often  necessary  to  plant  the  tubers  for  another 
year  or  two  in  order  to  secure  plants  which  will  bear  a 
normal  crop  of  good-sized  tubers.  The  tubers  should  be 
harvested  separately  for  each  plant,  put  in  paper  bags, 
and  carefully  stored  until  spring.  Usually  one  is  able 
to  make  his  final  selection  the  second  year,  but  in  some 
cases  it  is  necessary  to  plant  the  tubers  again  before  he 
can  be  sure  that  his  choice  of  strains  is  a  wise  one.  The 
tubers  should  be  planted  about  40  inches  apart  the  sec- 
ond year  to  allow  a  careful  study  of  individual  plants. 

One  ought  to  remember  that  it  is  comparatively  easy 
to  produce  new  varieties  of  plants,  and  that  the  mere 
fact  that  we  have  secured  new  sorts  does  not  mean 
that  they  are  worthy  of  culture.  Any  new  variety  of 
plant  should  be  distinctly  superior  to  others  on  the  mar- 
ket in  at  least  one  respect.  The  markets  are  already 
cluttered  with  mediocre  varieties.  Set  your  ideals  high  and 
do  not  be  content  with  anything  which  falls  short  of  them. 
Also  do  not  waste  time  trying  to  select  good  qualities  in 
strains  where  no  such  possibilities  exist.  Selection  will 
not  build  up  characters  which  are  not  potentially  present. 

In  spite  of  the  many  hindrances  to  hybridization,  some 
careful  studies  have  been  made  on  the  inheritance  of 
characters  in  the  potato.  We  must  remember,  however, 
that  in  some  cases  at  least,  the  material  studied  was  not 

»  Wilson,  J.  H.     High,  and  Agri.  Soc.  Scot.     Trans.  1907,  pp.  74-92. 
G 


82  The  Potato 

pure.  Perhaps  it  would  be  safest  to  look  upon  the  results 
as  showing  certain  tendencies  in  heredity,  rather  than  as 
accurate  character  analysis.  Salaman  ^  ^  of  England  and 
East  ^  of  this  country  have  done  most  of  the  mendelian 
work  on  the  potato.  A  resume  of  their  work  will  be  given 
in  the  sections  that  follow : 

Stem  color.  —  Some  varieties  of  potatoes  have  pure  green  stems, 
while  others  have  traces  of  purple  varying  from  light  purple  to  al- 
most black.  The  purple  seems  to  be  partially  dominant  over  the 
green.  The  pure  greens  appear  to  be  recessive  and  to  breed  true. 
Salaman  ^  found  that  the  deep  purple  stem  color  of  the  Congo  gave  a 
good  mendelian  segregation.     No  ratios  were  given. 

East  {loc.  cit.)  reports  the  following:  One  purple-stemmed  vari- 
ety when  selfed  gave  only  purples.  Four  piu-ple-stemmed  varieties 
gave  both  purple  and  green  when  selfed.  Four  green  varieties  when 
selfed  gave  only  green.  A  pure  green  X  a  heterozygous  purple  gave 
6  purples  and  7  greens  —  RR  X  DR. 

Flower  color.  —  Potato  flowers  may  be  either  white,  heliotrope  or 
shades  of  purple.  The  color  is  usually  confined  to  one  or  the  other  of 
the  surfaces  of  the  flower.  In  all  the  domestic  varieties  studied  by 
Salaman  {loc.  cit.)  the  color  was  limited  to  the  upper  surface.  S.  tube- 
rosum had  color  only  on  the  lower  surface.  In  S.  rcrrucosum  the 
color  appeared  to  be  present  on  both  sides  of  the  flower. 

East  {loc.  cit.)  reports  one  purple  which  broke  up  into  14  purples 
to  5  whites  when  selfed.  He  says  that  purple  is  probably  dominant 
to  white. 

Color  in  the  tubers.  —  The  skin  of  the  tuber  may  be  either  white 
(yellow),  red  or  purple.  The  flesh  in  like  manner  may  be  either 
white  or  colored.  Purple-skinned  varieties  often  have  white  flesh, 
and  white-skinned  sorts  may  show  traces  of  color  when  cut  open. 
Salaman  ^  says  that  these  colors  are  all  due  to  pigments  dissolved  in 
the  cell  sap. 

'  Salaman,  R.  N.  The  Inheritance  of  Color  and  Other  Characters  in 
the  Potato.     Journ.  Gen.,  Vol.  1,  1910-11. 

=  Salaman,  R.  N.  A  Lecture  on  the  Hereditary  Characters  of  the 
Potato.     Roy.  Soc.  Hort.  Journ.,  38  :   34-39  (1912-13). 

3  East,  E.  M.  Inheritance  in  Potatoes.  Amer.  Nat.,  U:  424-430 
(1910). 


Potato  Breeding  83 

East  found  that  purples  when  selfed  gave  in  some  cases  only 
purples;  in  other  cases,  purples  and  whites;  and  in  still  others, 
purples,  reds  and  whites.  Reds  when  selfed  gave  either  reds  alone, 
or  reds  and  whites.  Whites  gave  only  whites.  No  mosaics  of  red 
and  purple  were  obtained.  The  conclusion  was  that  red  is  epi- 
static  to  white,  and  purple,  to  both  red  and  white. 

Salaman  ^  selfed  a  red-tiibered  plant  of  the  variety  Flourball  and 
got  a  ratio  of  9  reds  :  7  whites,  suggestive  of  the  action  of  two  pairs 
of  factors.  He  believes  that  chromogen,  a  color  base,  is  present  in 
all  tubers.  In  the  red  tubers  he  assumed  the  action  of  an  R  factor 
for  color  and  a  D  factor  which  develops  R.  The  second  generation 
would  then  give  :  — 

9  RD     —  red 

3Rd] 

3rD  [  —  white 

Ird  J 

The  red-tubered  plant  which  Salaman  self-fertilized  was  assumed 
to  be  of  the  constitution  Rr  Dd. 

The  Congo  X  Flourball  (heterozygous  for  red)  gave  in  Fi  13 
black  :  12  red  :  4  white. 

Salaman  holds  that  a  factor  for  purple  —  P  —  is  necessary  in  addi- 
tion to  the  R  and  D  factors  to  give  purple.  He  has  on  four  different 
occasions  united  strains  bearing  white-skinned  tubers  to  get  colored 
types.  This  may  be  a  case  of  factor  interaction  similar  to  Bateson's 
case  of  complementary  colors  in  the  sweet  pea. 

Solarium  etuherosum  seems  to  have  an  inhibitor  to  the  formation 
of  purple  in  the  tubers. 

Flesh  color.  —  Very  little  work  has  been  done  on  this  character. 
Salaman  notes  that  the  color  of  flesh  is  inherited  independently  of 
skin  color.  He  says  that  colored  flesh  is  apparently  due  to  the 
action  of  one  pair  of  factors. 

Shape  of  tuber.  —  Both  East  and  Salaman  found  roundness  recessive 
to  other  shapes.  Round  jiotatoes  bred  true  in  all  cases.  Salaman 
found  that  long  tubers  bred  true  for  long  axis,  but  often  varied  in 
diameter  and  hence  in  shape.  Many  oval-shaped  potatoes  were 
found  to  be  heterozygous  and  to  break  up  when  selfed  into  round, 

'  Salaman,  R.  N.  The  Inheritance  of  Color  and  other  Characters  in 
the  Potato.     Journ.  Gen.,  Vol.  1,  1910-11. 


84  The  Potato 

oval  and  elongated.  The  kidney  and  cylindrical  shaped  tubers  have 
about  the  same  length  of  axis,  but  seem  to  have  different  factors  de- 
termining diameter. 

Depth  of  ei/es.  —  The  deep  eye  is  a  recessive  character  and  breeds 
true.  Shallow  eyes  are  dominant  over  deep  eyes,  but  often  not  com- 
pletely so. 

Steriliti/.  —  Salaman  ^  finds  that  a  tendency  toward  sterility  is 
dominant  over  a  fertile  condition  of  the  pollen.  In  a  cross  of  Record 
(no  pollen)  X  Flourball  (abundant  pollen),  the  Fi  generation  gave 
12  pollen-bearing  plants  and  20  wnth  no  pollen.  One  of  the  sterile 
(for  pollen)  Fi  plants  crossed  with  the  male  parent  used  above  gave 
19  pollen  bearing  to  20  non-pollen  bearing.  This  is  practically  the 
1  :  1  ratio  which  we  should  expect  to  get  from  a  cross  between  a 
heterozygous  and  a  pure  recessive. 

Stolon  length.  — The  stolons  on  which  the  tubers  are  borne  are  un- 
usually long  in  the  species,  S.  Commcrsonii  and  S.  verrucosum,  often 
reaching  6  feet  or  more.  In  the  domestic  varieties  the  stolons 
average  9-12  inches.  Very  long  and  very  short  stolons  breed  true. 
Intermediate  stolons  break  up  into  various  lengths,  suggesting  the 
action  of  multiple  factors.  Salaman  ^  thinks  there  may  be  two  or 
perhaps  three  pairs  of  factors  involved. 

Plant  habit.  —  Salaman  ^  states  that  upright  and  prone  habit  of 
plant  are  due  to  the  action  of  one  pair  of  factors.  A  duplex  condi- 
tion of  the  factor  for  uprightness  gives  a  perfectly  upright  plant. 
Heterozygotes,  Aa,  are  upright  at  first,  but  droop  toward  the  close 
of  the  season.  Prone  plants  have  the  constitution  aa.  Both  prone 
and  upright  plants  bred  true  to  type.  Intermediates  gave  a  ratio 
of  1  upright :  2  intermediates :  1  prone,  when  selfed. 

Shape  of  berry.  —  The  seed  berries  of  domestic  varieties  of  pota- 
toes are  round.  Those  of  the  wild  species  tend  to  be  long.  Salaman 
concludes  that  one  pair  of  factors  is  involved.  He  believes  the  long 
berries  to  be  due  to  a  du])lex  dose  of  a  factor  for  length.  When  the 
length  factor  is  simplex,  a  heart-shaped  berry  results.  The  double 
recessive  factor  gives  round  berries  which  breed  true  to  shape. 

'  Salaman,  R.  N.  A  Lecture  on  the  Hereditary  Characters  of  the 
Potato.     Roy.  Soc.  Hort.  Journ.,  38 :  34-39  (1912-13). 


Potato  Breeding  85 


REFERENCES 

East,  E.  M.     A  Study  of  the  Factors  Influencing  the  Improvement 

of  the  Potato.     III.  Bui.  127,  1908. 
East,  E.  M.     Inheritance  in  Potatoes.     Amer.  Nat.,  '44-'  1910,  pp. 

424-430. 
Fraser,  S.     The  Potato.     N.  Y.   (Orange  Judd  Co.),  1-185,  1901. 

Breeding  and  Selection,  pp.  171-177. 
Fruwirth,    C.     Die    Ziiclitung   der    landwirtschaftlichen    Kultur- 

pflanzen.     Vol.  3,  Berlin,  1905. 
New^ian,  L.     Plant  Breeding  in  Scandinavia.     Ottawa  (Can.  Seed 

Growers  Association),  1912,  pp.  193.     (Potatoes,  168-182.) 
Salaman,  R.  N.     The  Inheritance  of  Color  and  Other  Characters  in 

the    Potato.     Journ.    Gen.,  Vol.   1,    1910-11,  7-46,    pis.    I- 

XXIX. 
Stuart,  Wm.     Potato  Breeding  and  Selection.    U.  S.  D.  A.  Bui.  195 

(professional  paper),  1915,  pp.  35,  pis.  XVI,  figs. 
Waid,  C.  W.    Results  of  Hill  Selection  of  Potatoes.    Amer.  Breeders 

Association,  Ann.  Rept.,  Vol.  3,  1907,  pp.  191-199. 
Webber,  H.  J.     Methods  of  Breeding  and   Improvement  of  the 

Potato    Crop.      Cornell    Farmers'    Reading   Course   Bui.   43, 

1909,  pp.  753-768. 


CHAPTER  V 

CLIMATE,  SOILS  AND  ROTATION 

By  Daniel  Dean 

The  climate  of  most  parts  of  the  United  States  is  not 
well  suited  to  the  production  of  the  potato.  The  heat  of 
summer  is  too  great  and  the  water  supply  in  the  soil  and 
in  rainfall  during  the  growing  season  is  too  small.  It  is 
not  known  what  are  the  possibilities  of  the  potato  in  the 
mountain  regions  of  South  America  from  which  it  was 
brought  by  white  men  in  the  sixteenth  century,  but  it  is 
certain  that  up  to  the  present  time  growers  of  north- 
western Europe  have  often  secured  higher  yields  to  the 
acre  than  those  of  the  United  States.  One  great  reason 
for  this  fact  is  the  difference  in  climate.  The  most  famous 
potato-growing  regions  of  Europe  are  several  degrees 
north  of  any  part  of  the  United  States,  except  Alaska. 
The  average  summer  heat  of  northern  Germany  is  esti- 
mated by  the  United  States  Department  of  Agriculture  at 
nearly  ten  degrees  Fahrenheit  lower  than  that  of  most  of 
the  potato-growing  sections  of  the  United  States.  The 
climate  of  the  principal  potato-growing  regions  of  Europe 
is  so  cool  that  Indian  corn  is  not  grown  in  them,  while 
there  is  heat  enough  for  corn  in  most  of  the  northern 
United  States  and  even  for  cotton  in  the  South.  Most 
of  northwestern  Europe  has  very  heavy  rainfall  because 
of  the  Gulf  Stream.  The  potato  is  grown  in  the  United 
86 


Climate,  Soils  and  Rotation  87 

States  because  of  its  high  value  for  human  food,  not  be- 
cause of  favorable  conditions.  These  facts  are  emphasized 
because  knowledge  of  the  nature  of  the  potato  plant  helps 
the  grower  to  adapt  his  methods  to  his  local  conditions 
to  secure  the  best  results.  Except  in  northern  Maine 
and  the  adjoining  provinces  of  Canada,  there  are  few 
parts  of  America  w^  here  summer  heat  and  moisture  do  not 
limit  the  yield  of  the  potato  to  a  figure  below  the  best 
possibilities  of  the  plant.  Methods  which  prevent  the 
effects  of  these  two  factors  result  in  largely  increased 
yields.  In  occasional  seasons,  as  in  parts  of  New  York 
in  1909  and  1914,  the  climate  is  favorable  and  large  yields 
are  grown.  It  might  be  possible  in  such  years  to  get 
yields  equal  to  those  of  northwestern  Europe,  but  it 
would  be  necessary  to  equal  their  large  expenses  for  addi- 
tional labor,  seed  and  fertilization  and  this  w'ould  result 
in  heavy  loss  in  the  other  years  when  climate  limited  the 
yield.  Hot  and  dry  years  are  known  in  Europe,  but  are 
the  exception  instead  of  being  the  rule  as  in  most  of  the 
United  States. 

The  United  States  Department  of  Agriculture  Year- 
book for  1914  gives  the  average  yield  of  potatoes  to  the 
acre  for  the  whole  United  States  for  ten  years  as  being 
96  bushels,  while  that  of  the  state  of  Maine,  with  cool  and 
damp  climate,  for  the  same  period,  was  206  bushels. 
The  figures  for  the  countries  of  northwestern  Europe  are 
311  for  the  Netherlands,  388  for  Belgium,  210  for  Great 
Britain  and  Ireland  and  200  for  Germany.  Yields  are 
lower  in  the  warmer  or  drier  countries  of  Europe,  being 
130  in  France,  115  in  Hungary  and  106  in  Russia.  A 
similar  contrast  is  marked  between  hot  Australia  with  an 
average  of  101  bushels  and  cool  New  Zealand  with  216, 
though  both  are  settled  by  the  same  race  of  people. 


88  The  Potato 

The  warmest  province  of  Canada,  Ontario,  averages  121 
against  207  for  the  cool  and  moist  maritime  provinces 
and  229  for  British  Columbia. 

Land  is  much  higher  in  price  in  the  potato-growing 
regions  of  Europe  than  in  America.  An  extreme  case  is 
on  the  Island  of  Jersey,  where  land  is  worth  $1000  to 
S2500  an  acre.  The  annual  rental  under  the  tenant  sys- 
tem common  in  Europe  is  often  higher  than  the  sale 
value  of  an  acre  in  sections  of  the  United  States  which 
raise  millions  of  bushels  each  year.  Labor  is  much 
cheaper  in  Europe  than  in  America,  allowing  the  use  of 
very  intensive  hand  culture  at  low  cost.  If  European 
growers  are  to  secure  a  living  profit  above  their  high 
rentals,  they  must  farm  this  high-priced  land  very  inten- 
sively with  large  expenditure  of  cheap  labor,  seed  at 
the  rate  of  an  average  of  over  37  bushels  to  the  acre  and 
heavy  fertilization. 

American  agriculture  has  been  developed  in  the  direc- 
tion of  heavy  production  to  each  worker  engaged  rather 
than  in  that  of  large  yield  to  the  acre.  The  high-priced 
day's  work  is  the  unit,  not  the  high-priced  acre  of  land. 
From  the  time  when  the  Massachusetts  Bay  colonists 
"went  west"  to  the  Connecticut  Valley  in  1635,  it  was 
necessary  to  go  westward,  even  to  northwestern  Canada, 
for  there  has  been  a  new  region  of  cheap  land  awaiting 
settlement.  Almost  until  the  present  time,  the  competi- 
tion of  new  soil  of  virgin  fertility  has  kept  down  the  price 
of  farm  produce  and  of  land  in  the  older  settled  communi- 
ties to  figures  far  below  those  of  Europe.  An  even  worse 
effect  of  this  competition  has  been  that  little  attempt  has 
been  made  to  keep  up  soil  fertility.  Methods  of  farming 
suited  to  frontier  conditions  of  low  prices  and  highly 
fertile  soil  have  continued  in  use  too  long.     Land  is  now 


Climate,  Soils  and  Rotation  89 

rapidly  rising  in  price,  and  methods  of  increasing  the  yield 
of  crops  will  become  more  important  than  before. 

The  high  cost  of  labor  in  the  United  States  compared 
with  that  of  land  has  resulted  in  the  invention  and  use 
of  labor-saving  machinery  for  nearly  every  process  of 
farming  by  which  the  power  of  horses  or  of  engines  has 
displaced  that  of  human  muscle.  Machinery  cannot  so 
much  increase  the  production  to  an  acre  as  the  production 
to  each  worker  engaged  in  farming  by  increasing  the  num- 
ber of  acres  farmed  by  each.  For  example,  the  use  of 
horse-drawn  tools  compels  a  wider  spacing  of  potato 
rows  than  where  most  of  the  work  is  by  hand  labor. 
This  reduces  the  yield  to  the  acre  by  reducing  the  num- 
ber of  plants.  On  the  island  of  Jersey,  rows  of  potatoes 
are  spaced  16  inches  apart  and  24  to  27  in  other  parts  of 
Europe,  compared  with  33  to  42  in  America. 

FACTORS   INFLUENCING    POTATO    CULTURE 

Study  of  the  factors  governing  the  choice  of  methods 
for  the  culture  of  the  potato  shows  that  eight  are  of  prin- 
cipal importance:  (1)  heat  in  air  and  soil;  (2)  water; 
(3)  soil  texture ;  (4)  available  plant-food ;  (5)  drain- 
age and  soil  air;  (6)  the  "critical  period"  in  the  life  of 
the  plant ;  (7)  type,  variety  and  strain  of  the  seed ; 
(8)  diseases. 

The  term  "limiting  factor"  is  frequently  used  in  other 
connections  and  is  peculiarly  appropriate  in  potato- 
growing.  Any  one  of  the  above  factors  may  be  inhibiting 
in  some  conditions  and  may  be  able  to  place  a  limit  on 
the  size  of  the  crop  which  cannot  be  removed  by  the 
others  being  favorable.  For  example,  all  farmers  are 
familiar  with  the  loss  of  yield  caused  by  drouth,  although 


90  The  Potato 

not  all  know  that  the  direct  effect  of  great  heat  is  per- 
haps even  more  harmful  than  the  lack  of  water.  The 
results  of  unchecked  attacks  of  insects  like  the  Colorado 
potato-beetle  or  of  the  late  blight  and  rot,  are  other 
familiar  examples.  The  potato-grower  who  would  raise 
good  yields  every  year  through  a  series  of  years  must 
study  very  carefully  every  factor  which  enters  into  the 
growing  of  potatoes  under  his  particular  conditions, 
with  the  idea  of  making  sure  that  no  one  condition 
will  limit  the  results  of  his  labor  in  other  directions. 
Such  care  counts  heavily  in  increasing  the  income  of  the 
farm,  because  seasons  in  which  a  crop  is  generally  poor 
from  any  cause  are  the  ones  in  which  prices  are  high. 

Heat 

Numerous  experiments  have  shown  that  temperatures 
in  the  soil  above  certain  limits  injure  the  vitality  of  the 
potato  plant.  The  extent  of  the  injury  depends  on  the 
degree  of  heat  and  on  other  injurious  factors,  as  drouth 
and  insQct  injury.  The  effect  varies  from  reduction  in 
yield  to  practical  failure  with  tubers  ruined  for  use  as 
seed.  Potatoes  are  not  grown  in  the  South  in  midsum- 
mer. When  grown  in  the  months  of  late  winter  and  spring, 
the  vitality  of  the  tubers  for  use  as  seed  is  ruined  by  the 
heat  at  the  time  the  tubers  mature.  The  "second-crop" 
for  seed  in  the  South  is  planted  in  July  or  August  and 
forms  its  tubers  in  the  cool  weather  of  late  fall.  At  this 
time  seed  of  good  vitality  is  obtained.  Near  the  Canadian 
line  and  in  the  Rocky  Mountain  region  there  is  little  more 
time  in  the  whole  growing  season  than  is  needed  by  the 
late  main-crop  varieties.  When  hot  seasons  occur  there, 
as  at  Ottawa,  Canada,  in  190G-7-8,  and  at  Greeley,  Colo- 


Climate,  Soils  and  Rotation  91 

rado,  in  1911,  there  is  no  way  of  avoiding  the  heat  by 
early  or  late  planting.  In  intermediate  sections  like  those 
from  Long  Island  through  to  Iowa,  growers  avoid  the 
effects  of  summer  heat  to  some  extent  by  planting 
either  very  early  or  very  late. 

Another  method  used  more  or  less  unconsciously  by 
growers  to  prevent  the  effects  of  summer,  is  the  use  of 
heat-resistant  varieties.  The  INIcCormick  or  Late  Hoosier 
is  used  in  Virginia  and  INIaryland  in  summer  because  of 
its  peculiar  ability  to  produce  crops  in  weather  too  hot 
for  any  other  variety.  The  Rural  or  Blue-Sprout  type 
is  the  one  which  is  grown  more  than  any  other  in  the 
LTnited  States.  It  owes  much  of  its  popularity  to  the 
fact  that  it  will  yield  well  in  hot  and  dry  seasons.  The 
use  of  the  Green  INIountain  or  White-Sprout  type  is 
mainly  confined  to  the  cooler  sections,  like  INIaine,  because 
of  its  inability  to  stand  heat  as  well  as  the  Rural  type. 
The  Triumph,  Cobbler  and  Early  Ohio  types  are  used  to 
avoid  extreme  heat  by  growth  in  early  spring  rather  than 
by  heat  resistance. 

Heat  is  such  a  decisive  factor  in  the  growth  of  potatoes 
in  most  of  the  United  States  that  growers  must  ever  keep 
its  effects  in  mind  if  they  are  to  succeed  with  the  crop. 
Many  of  these  methods  of  culture  now  used  have  been 
forced  on  growers  unconsciously  by  the  influence  of  heat 
on  the  plant.  ]\Iuch  is  to  be  expected  in  the  future  from 
further  investigations.  Straw  mulches  have  been  found 
very  beneficial  in  the  hot  regions  of  the  western  plains  to 
insure  coolness  in  the  soil.  It  has  been  proved  that 
thorough  spraying  with  bordeaux  mixture  greatly  reduces 
the  injury  from  heat.  This  is  shown  by  some  of  the 
gain  from  spraying  in  hot  seasons  when  blight  and  insect 
injury  are  absent.     A  possibility  is  in  the  use  of  over- 


92  The  Potato 

head  irrigation  in  humid  sections.  One  of  the  greatest 
needs  of  potato-growers  everywhere  is  a  new  variety 
possessing  the  table  quahty,  yield  and  appearance  of 
those  now  in  use  together  with  the  heat-resistance  of  the 
McCormick. 

Water  requirements 

Lack  of  sufficient  water  is  often  a  Hmiting  factor  on 
the  yield  of  potatoes.  Many  experiments  indicate  that 
about  400  tons  of  water  are  used  by  the  potato  plant  for 
each  ton  of  dry  matter  produced,  or  over  three  tons  for 
each  bushel.  This  equals  3  inches  of  rainfall  for  each 
100  bushels  to  the  acre.  Study  of  Weather  Bureau 
records  of  rainfall  shows  that  the  average  amount  in  the 
entire  growing  seasons  in  most  potato-growing  sections 
is  only  10  to  18  inches.  The  losses  from  run-off  and 
from  evaporation  are  so  heavy  that  this  factor  must 
be  provided  for  if  exceptional  yields  are  to  be  raised. 
Methods  of  conserving  the  soil  water  left  by  winter  rains, 
for  the  use  of  the  crop,  are  of  great  value.  The  use 
of  ordinary  surface  irrigation  in  the  West  and  of  over- 
head irrigation  in  the  East  produces  much  heavier  yields 
than  when  rainfall  is  the  whole  dependence.  With  these 
methods,  yields  of  over  500  bushels  to  the  acre  are  common. 

Surface  tillage  to  prevent  evaporation  and  the  incor- 
poration of  organic  matter  with  the  soil  are  the  principal 
means  of  conserving  moisture.  Plants  on  rich  soil  or 
when  manures  or  fertilizers  are  used,  are  able  to  secure 
their  plant-food  from  the  soil  by  the  use  of  less  water 
than  when  grown  on  poor  soil.  Any  means  of  extend- 
ing the  growth  of  roots  makes  more  water  available. 
The  great  need  of  water  for  the  potato  crop  comes  at  the 
time  when  the  tubers  are  forming.     It  is  a  matter  of 


Climate,  Soils  and  Rotation  93 

common  observation  that  a  small  amount  of  rainfall  at 
this  time  may  be  worth  much  more  than  larger  amounts 
at  other  times.  As  this  comes  immediately  after  the 
critical  period  in  the  life  of  the  potato,  it  will  be  seen  that 
every  effort  should  be  made  to  keep  the  plant  well  sup- 
plied with  water  by  tillage,  organic  matter,  and  the  like. 

Soil  texture 

The  root  system  of  the  potato  is  weak  and  small  com- 
pared with  that  of  other  standard  farm  crops,  such  as 
corn.  It  is  especially  weak  in  penetrating  heavy  soils. 
In  any  soil,  loose  texture  greatly  favors  the  potato  by  allow- 
ing wider  and  deeper  distribution  of  the  roots.  The  de- 
velopment of  the  tubers  is  checked  and  rendered  irregular 
unless  the  soil  is  loose  and  open  in  texture.  Most  of  the 
early  crop  for  sale  in  summer  is  grown  on  sandy  soils. 
On  account  of  their  advantages  in  structure,  potatoes  would 
be  raised  only  on  sandy  soils  did  they  not  have  other  dis- 
advantages which  offset  the  value  of  good  structure  and 
earliness.  Too  great  soil  heat  and  lack  of  moisture  often 
limit  the  yield  of  potatoes  grown  on  sandy  soils  as  a  late 
main  crop  in  summer.  Much  of  the  w^ork  of  the  potato- 
grower  must  be  directed  to  give  heavier  soil  types  a  struc- 
ture more  loose  and  open.  Increasing  the  proportion  of 
organic  matter  loosens  up  the  structure  of  soils.  Some  of 
the  greatest  potato-growing  soils  naturally  possess  plenty 
of  organic  matter,  as  the  Aroostook  soils  and  the  tule 
lands  of  California.  The  increased  value  of  irrigated 
soils  for  the  potato-growing  where  organic  matter  is  sup- 
plied by  rotation  with  alfalfa,  or  the  use  of  humus-produc- 
ing cover  crops  in  the  South,  shows  the  importance  of  or- 
ganic matter.     There  are  few  American  soils  which  are  not 


94  The  Potato 

improved  for  the  potato  by  increasing  their  organic  matter 
content.  Under  most  American  methods  of  cultivation 
the  proportion  is  reduced ;  consequently  yields  are  grad- 
ually' reduced,  and  in  the  case  of  some  varieties,  like  the 
Burbank,  even  the  shape  of  the  tubers  may  be  injured 
by  development  in  the  less  mellow  soil.  Cheap  and  easy 
methods  for  the  increase  of  the  supply  of  organic  matter 
are  among  the  greatest  needs  of  potato-growers. 


Available  plant-food 

For  several  reasons  the  potato  is  less  able  to  secure  its 
plant-food  from  the  soil  as  well  as  many  other  plants  un- 
less it  is  in  readily  available  condition.  For  example,  the 
use  of  insoluble  phosphoric  acid  in  the  form  of  raw  rock 
phosphate  often  gives  good  results  on  other  crops  but 
seldom  on  the  potato.  A  large  supply  of  organic  matter 
in  the  soil,  good  drainage  and  a  slightly  alkaline  condition 
are  essential  to  the  liberation  of  the  stores  of  plant-food 
in  the  soil  for  the  use  of  plants.  Fertilizers  do  not  pro- 
duce their  full  effect  on  potatoes  unless  these  conditions 
are  present.  If  the  latter  are  favorable,  fertilizers  seldom 
fail  to  increase  the  yield.  The  use  of  fertilizers  on  potatoes 
is  increasing  very  rapidly.  In  Maine,  Long  Island,  New 
Jersey  and  through  the  coast-trucking  section  from  Nor- 
folk to  Florida,  over  a  ton  to  the  acre  is  often  used.  The 
value  of  potatoes  for  human  food  is  so  high  that  the  price 
received  for  the  crop  makes  such  use  profitable.  There  is 
also  a  residual  effect  of  the  fertilizer  on  the  succeeding 
crops  of  a  rotation,  to  be  considered.  Part  of  this  effect 
may  be  due  to  a  favorable  effect  of  fertilizers  on  the  soil 
bacteria.^ 

1  U.  S.  D.  A.  Off.  of  Exp.  Sta.  Bui.  194. 


Climate,  Soils  and  Rotation  95 

Drainage  and  soil  air 

All  crops  require  more  or  less  air  in  the  soil  for  health 
and  growth.  The  need  of  air  in  the  soil  is  one  reason 
why  potatoes  do  poorly  on  too  heavy  clay  soils.  One 
reason  for  the  ridge  culture  so  much  used  on  wet  or  heavy 
soils  like  those  of  the  Aroostook  region  and  the  volusia 
soils  region  is  the  need  of  drainage  and  soil  air.  Air  is 
necessary  to  the  work  of  bacteria  in  the  soil  and  to  the 
chemical  changes  which  make  plant-food  available  in 
it.  Water  is  necessary  to  plant  growth,  but  too  much 
in  the  soil  is  injurious.  Tile-drainage  removes  the  sur- 
plus of  water  quickly  after  rains  and  so  extends  down- 
ward the  area  in  which  roots  can  live.  Western  potato- 
growers  who  irrigate  have  learned  to  apply  the  water  in 
furrows  between  the  rows.  The  rows  are  ridged  high 
enough  to  allow  the  forming  tubers  and  a  large  part  of 
the  root  system  to  remain  above  the  level  of  the  water  in 
the  furrows.  The  potato  is  very  sensitive  to  the  presence 
of  too  much  water  in  the  soil.  This  is  shown  by  the 
quickness  with  which  potatoes  die  after  being  covered 
by  floods  or  by  standing  water  after  rains.  The  immer- 
sion of  the  tops  for  a  few  days  or  even  hours  is  fatal. 
Too  much  water  in  the  soil  will  kill  part  of  the  roots,  and 
greatly  reduces  the  vitality  of  the  plants. 

Critical  period 

The  potato  is  now  very  different  from  the  wild  plant 
before  its  domestication.  Then  it  produced  few  tubers, 
and  these  were  very  small.  The  present  varieties  have 
been  produced  from  the  original  wild  stock  by  hun- 
dreds of  years  of  breeding  and  selection  to  meet  the  de- 


96  The  Potato 

mands  now  made  upon  the  plant.  The  yield  of  tubers 
has  been  enormously  increased  above  that  of  the  wild 
plant.  Many  shapes  and  colors  have  been  discarded  to 
keep  the  few  which  suit  the  eyes  of  civilized  men.  The 
length  of  the  life  of  the  potato  plant  has  been  shortened 
from  nine  months  or  more  in  the  wild  state  to  only  three 
or  four  months.  Vast  numbers  of  seedling  varieties 
which  may  have  possessed  greater  natural  vigor  have 
been  discarded  to  keep  those  which  possess  these  quali- 
ties. It  is  not  surprising  therefore  that  the  potato  plant 
is  not  a  strong  one.  One  period  in  its  life  is  especiall}^ 
precarious.  The  cultivated  plant  now  produces  much 
less  seed  than  the  wild  plant,  some  kinds  seldom  or  never 
blossoming;  but  blossoming  is  still  a  demand  upon  the 
strength  of  the  potato.  In  the  wild  state  the  tubers  were 
set  after  the  seed  formation.  Under  domestication  the 
life  of  the  plant  has  been  shortened  and  the  two  processes 
overlap.  When  this  time  comes  in  hot  weather,  as  with 
the  late  main  crop  of  the  northern  states,  the  heat  and 
drought  which  occur  so  often  make  the  poorest  possible 
conditions  for  the  potato.  Insects,  diseases  and  careless 
methods  of  cultivation  often  further  reduce  the  vitality 
of  the  crop.  This  has  been  called  the  "critical  period" 
of  the  life  of  the  potato.  If  it  is  passed  in  high  \-ig<)r,  the 
potato  has  later  a  more  or  less  indeterminate  growth. 
That  is,  there  is  no  clearly  defined  time  for  its  maturity, 
as  with  grain  crops,  but  instead  it  gradually  weakens,  all 
the  time  increasing  the  yield  of  tubers.  This  condition 
occurs  but  seldom  in  the  United  States  on  account  of  the 
heat  of  summer,  but  it  is  an  ideal  towards  which  potato 
growers  should  strive.  Production  of  a  high  degree  of 
vitality  in  the  growing  plant  in  its  early  life  and  good 
soil  conditions  and  care  during  the  hot  weather,  will  carry 


Climate,  Soils  and  Rotation  97 

the  crop  safely  through  heat  and  drought  which  would 
not  only  badly  reduce  the  yield  but  also  spoil  the  crop 
for  use  as  seed.  Practically  the  whole  yield  is  produced 
after  this  time. 

Type,  variety  and  strain 

In  this  chapter,  reference  to  the  seed  used  is  made  to 
show  that  the  variation  between  different  types,  varieties 
and  strains  allows  the  grower  considerable  latitude  in 
adjusting  the  potato  crop  to  different  conditions.  The 
use  of  quickly  maturing  types  in  the  South  and  of  heat- 
resistant  types  in  all  but  the  most  northern  sections  are 
examples  of  these  adaptations.  Much  effort  has  been 
expended  in  the  effort  to  find  new  varieties  possessing  the 
quality  of  resistance  to  some  of  the  more  serious  potato 
diseases,  but  with  little  success  as  yet. 

Diseases 

Several  of  the  most  important  potato  diseases  affect 
cultural  methods.  Examples  of  such  are  the  use  of  long 
rotation  to  eliminate  common  scab,  rhizoctoniose,  the 
nematode  eel  worm  and  the  fusarium  wilt,  from  affected 
soils.  Early  spring  planting  to  insure  maturity  before  pos- 
sible attacks  of  late-blight  is  employed  in  some  sections. 


GENERAL    TYPES     OF     POTATO-GROWING     IN    THE     UNITED 
STATES 

Conditions  of  climate,  soil,  seed  and  markets  vary  so 
much  that  every  grower  has  his  problem  to  select  the 
methods  which  will  give  him  the  most  profitable  results. 
The   climate   is   something  the   grower   cannot   change. 


98  The  Potato 

The  markets  have  demands  which  the  individual  can  do 
little  to  change.  But  in  the  selection  of  methods  he  has 
wide  range  of  choice.  The  great  variation  in  the  climates 
and  soils  of  as  large  a  country  as  the  United  States  makes 
for  a  wide  range  in  culture  methods.  Broadly  speakmg, 
most  of  the  potato-growing  of  the  United  States  may  be 
divided  into  five  general  types : 

(1)  The  early  truck  crop  of  the  southern  states,  extend- 
ing to  about  the  latitude  of  Washington.  This  belt  is 
characterized  by  extreme  summer  heat  which  prevents 
growth  in  summer,  excepting  that  of  the  heat-resistant 
McCormick  variety.  The  crop  is  grown  in  the  cool 
months  of  winter  and  spring  for  shipment  to  city  markets 
because  too  perishable  to  store  in  the  hot  summer.  Most 
of  the  seed  is  imported  from  the  north  or  grown  in  the 
cool  fall  months  as  a  "second  crop."  Commercial  fer- 
tilizers are  heavily  used  in  this  belt.  The  summer  heat 
does  not  permit  growth  of  most  of  the  perennial  hay  crops 
used  in  other  sections.  Annuals  are  mainly  used  for  hay 
and  for  the  cover-crops  that  are  often  raised  to  prevent 
erosion  and  loss  of  plant-food  in  winter.  Owing  to  the 
higher  prices  for  extreme  earliness,  only  short-season  early 
maturing  varieties  are  used  and  these  are  usually  dug 
immature.    Less  machinery  is  used  than  in  other  sections. 

(2)  The  northern  belt  of  the  principal  potato-producing 
states.  This  extends  from  Maine  to  North  Dakota  and 
down  to  the  latitude  of  New  York  City.  This  belt  sup- 
plies the  cities  and  southern  states  during  the  fall  and 
winter  and  competes  with  the  southern  truck  crop  from 
April  to  July.  The  climate  here  is  cool  enough  for  the 
potato  to  maintain  its  vitality  in  most  seasons,  if  given 
good  care.  Early  varieties  are  now  grown  but  little 
except  for  shipment  South  as  seed  stock.     The  use  of  fer- 


Climate,  Soils  and  Rotation  99 

tilizers  is  steadily  increasing,  being  very  heavy  in  the 
East  from  Maine  to  New  York,  Spraying  with  bordeaux 
mixture  for  the  late  blight  and  rot  is  prevalent  in  the  East. 
Digging  comes  so  near  to  freezing  weather  that  the  gnan 
crops  grown  in  rotation  with  potatoes  are  those  sown  in 
spring.  Oats  are  used  mostly  with  spring  wheat  in  the 
Red  River  section.  Oats  and  peas  and  barley  are  grown 
to  less  extent. 

(3)  An  intermediate  belt  between  these  two  from 
Nebraska  to  New  Jersey  and  Long  Island.  Potatoes 
from  this  belt  come  on  city  markets  in  summer  and  early 
fall,  part  being  stored  for  winter  shipment.  Summer  heat 
is  not  so  dangerous  as  in  the  South,  but  there  is  usually 
an  effort  to  avoid  its  effects  to  some  degree  either  by 
planting  early  enough  to  get  the  crop  nearly  mature 
before  midsummer  or  else  late  enough  to  have  much  of 
the  growth  come  in  the  cool  fall  months.  The  effect  of 
summer  heat  on  seed  vitality  is  often  severe,  but  a  large 
share  of  the  seed  is  grown  locally.  The  use  of  imported 
seed  from  the  North  is  increasing,  particularly  in  the 
regions  of  more  intensive  culture,  such  as  Long  Island. 
Winter  wheat  and  rye  often  follow  the  potato  in  rotation 
in  this  belt. 

(4)  The  irrigated  sections  of  the  West,  destined  to 
great  extension  in  the  future.  The  problems  of  the 
potato-grower  in  other  sections  are  here  largely  replaced 
by  those  peculiar  to  the  growth  of  the  crop  under  irriga- 
tion. New  systems  of  culture  have  been  worked  out  to 
meet  the  new  conditions.  Control  of  moisture  has  en- 
abled some  of  the  heaviest  yields  ever  grown  in  the 
United  States.  Owing  to  the  natural  high  fertility  of 
arid  soils,  fertilizers  are  unknown.  Nitrogen  and  organic 
matter  are  secured  by  rotation  with  alfalfa. 


100  The  Potato 

(5)  Potato-growing  by  the  so-called  dry-farming  methods, 
and  local  conditions  such  as  the  delta  section  of  California, 
are  as  yet  less  important  types. 

SOILS 

The  choice  of  the  soil  on  which  to  grow  the  potato  is 
peculiarly  difficult  because  of  the  fact  that  those  which 
best  meet  the  needs  of  the  plant  in  one  respect  may  be 
unfitted  for  it  in  others.  Sandy  soils  permit  free  develop- 
ment of  the  root  system,  are  well  drained  and  are  capable 
of  early  tillage  in  spring.  Although  usually  poor  soils 
unless  fertilizer  is  applied,  the  growth  of  the  crop  is  rapid  ; 
and  for  these  reasons  most  of  the  early  truck  crop  of  the 
South  is  grown  on  sandy  soils,  as  earliness  secures  the 
highest  prices.  The  great  problem  of  potato-growing  on 
sandy  soils  is  that  of  sufficient  water  supply  at  the  time 
the  tubers  are  forming.  This  tendency  to  drought  and 
heat  injury  of  the  crop  has  operated  to  lessen  the  use  of 
sandy  soils  in  the  northern  states  for  the  late  main  crop 
In  favor  of  soils  cooler  and  more  retentive  of  moisture. 
A  large  proportion  of  organic  matter  is  of  great  value  to 
sandy  soils  in  increasing  available  fertility  and  the  ability 
to  hold  moisture.  The  organic  matter  in  sandy  soils  is 
easily  exhausted  by  tillage,  and  constant  effort  is  needed 
to  keep  it  up  to  a  high  standard. 

The  larger  part  of  the  potato  crop  of  the  United  States 
is  grown  on  soils  ranging  in  texture  from  sandy  or  gravelly 
loam  to  clay  loam.  Such  soils  are  capable  of  holding 
enough  moisture  to  supply  the  growing  plant  continu- 
ously, are  cooler  than  the  sands,  and  are  usually  of  fair 
fertility  if  not  too  deficient  in  organic  matter.  While  the 
extension  of  the  roots  and  the  formation  of  the  tubers 


HH^'"^ 

L^ 

E 

^^ 

i 

^^^^1 

Plate  VIII. 


Seed  potatoes.     Top,  different  ways  of  cutting. 
torn,  good  and  bad  types  for  seed. 


Bot- 


Climate,  Soils  and  Rotation  101 

are  not  as  easy  as  in  sandy  soils,  these  types  are  not  heavy 
enough  to  prevent  success  with  the  potato.  Clay  soils 
are  too  hard  and  heavy  for  the  potato.  Too  much  water 
at  times  and  poor  ventilation  often  affect  the  health  of 
potatoes  on  clays.  Careful  tillage,  tile  drainage  and  the 
incorporation  of  organic  matter  lighten  clay  soils  until 
they  will  produce  good  crops  of  potatoes  in  most  years. 
Except  in  special  cases,  as  near-by  markets,  it  usually 
pays  better  to  grow  potatoes  on  lighter  soils  and  use  the 
clay  soils  for  crops  more  adapted  to  them,  as  grass. 
Muck  soils,  as  the  tule  lands  of  California,  often  produce 
large  yields  of  potatoes.     The  quality  is  likely  to  be  poor. 

The  importance  of  organic  matter  in  the  soil  is  seldom 
fully  appreciated  by  American  farmers.  Most  American 
soils  outside  of  the  arid  regions  contained  more  organic 
matter  when  first  brought  under  cultivation  than  now. 
The  gradual  depreciation  from  year  to  year  is  not  noticed 
until  heavy  loss  in  fertility  has  occurred.  Another  cause 
which  has  contributed  to  the  depreciation  of  American 
soils  is  the  low  price  of  farm  produce.  The  Department 
of  Agriculture  estimates  the  cash  labor  income  of  Ameri- 
can farmers  to  average  about  $320  a  year  besides  the 
items  secured  from  the  farm  as  house-rent,  garden,  and 
the  like.  Too  often  this  condition  leads  to  robbery  of 
the  farmer's  capital,  the  soil.  The  settlement  of  the  last 
free  land  has  led  to  a  rise  of  the  prices  of  farm  products, 
which  now  makes  it  profitable  to  replace  and  increase  the 
lost  organic  matter  and  lime  fertility  of  older  soils. 

Organic  matter  has  great  power  to  absorb  water  and 
hold  it  for  the  use  of  plants.  The  potato  is  very  sus- 
ceptible to  injury  from  lack  of  water,  making  this  property 
of  organic  matter  of  great  value.  The  physical  nature  of 
any  soil  is  greatly  changed  by  organic  matter.     Heavy 


102  The  Potato 

soils  are  lightened,  often  to  a  degree  which  insures 
success  instead  of  failure  with  the  potato.  Sandy  soils 
are  improved  by  their  particles  being  bound  together. 
The  presence  of  abundant  organic  matter  makes  the  soil 
more  healthy  as  a  home  for  plants  and  for  the  beneficial 
soil  bacteria.  Both  need  water  and  air.  The  plant-food 
in  the  organic  matter  is  in  condition  to  feed  the  crop  as 
fast  as  it  decays  and  breaks  down.  Indirectly  the  decay 
helps  to  dissolve  the  mineral  plant-food  in  the  soil. 

Many  kinds  of  bacteria  and  other  microscopic  forms  of 
plant  life  are  found  in  the  soil.  Their  action  and  value 
are  seldom  understood  by  farmers.  Too  often  the  word 
"bacteria"  conveys  only  the  idea  of  disease,  or  at  most 
that  of  the  particular  bacteria  associated  with  legumes 
to  take  nitrogen  from  the  air.  These  latter  form  but  a 
fraction  of  the  microscopic  life  of  the  soil,  part  of  which 
is  beneficial  and  part  detrimental.  Organic  matter  in 
and  on  the  surface  of  soils  is  the  food  of  many  kinds  of 
bacteria,  and  is  broken  down  by  them  to  forms  which 
plants  can  assimilate.  The  nitrogen  of  organic  matter 
is  changed  first  to  ammonia  and  then  to  the  soluble 
nitrate  form.  Other  bacteria  like  the  azotobacter  group 
take  nitrogen  directly  from  the  air  without  being  asso- 
ciated with  any  particular  plants.  The  solution  of 
mineral  plant-foods  is  helped  by  some  kinds  of  bacteria. 
The  statement  is  generally  true  that  the  fertility  of  a  soil 
varies  according  to  the  number  of  bacteria  present.  The 
number  of  the  beneficial  forms  is  increased  by  attention 
to  maintaining  the  best  conditions  for  their  growth,  as  a 
large  supply  of  organic  matter  for  their  food,  an  alkaline 
soil,  sufficient  water  but  not  too  much,  and  sufficient 
soil  air. 

Organic  matter  in  the  soil  is  of  so  great  importance  to 


Climate,  Soils  and  Rotation  103 

the  potato  crop  that  methods  for  maintaining  its  supply 
need  careful  study.  In  the  natural  wild  state  the  soils 
of  humid  regions  receive  constant  additions  of  organic 
matter  from  the  death  of  plants  and  the  leaves  of  trees. 
The  richness  of  newly  cleared  forest  land  and  of  the  west- 
ern prairies  when  first  broken  are  examples  familiar  to  all. 
Under  cultivation  most  crops  annually  produce  more 
organic  matter  than  do  wild  plants,  but  in  most  cases  only 
a  fraction  is  returned  to  the  soil.  Part  is  shipped  away 
from  the  farm  for  the  use  of  man  or  of  animals,  part  is 
destroyed  by  the  animals  fed  on  the  farm  in  the  process  of 
digestion  and  part  is  lost  in  handling  the  manure.  Opera- 
tions of  tillage  and  exposure  of  bare  soils  to  the  air  rapidly 
use  up  organic  matter.  A  few  American  soils  are  being 
handled  in  waj's  which  increase  their  organic  matter,  but 
most  of  them  probably  are  not. 

The  principal  method  of  maintaining  soil  organic 
matter  is  that  of  crop  residues.  All  crops  leave  part 
of  their  organic  matter  in  the  soil  after  being  harvested, 
the  proportion  varying  greatly.  When  potato  tops  are 
burned  to  prevent  disease,  very  little  organic  matter  is 
left  in  the  soil  from  the  roots.  Other  plants  have  more 
extensive  root  systems  and  also  leave  other  residues  in 
the  form  of  stubble.  A  larger  proportion  is  left  when 
only  the  grain  or  seed  of  crops  is  removed  and  all  stalks 
or  straw  is  left  on  the  land.  Feeding  off  crops  in  the 
field,  as  in  "hogging  down"  corn,  leaves  all  the  organic 
matter  except  that  destroyed  in  the  process  of  digestion. 
In  practice,  hay  crops  leave  more  residues  than  others 
like  grain  and  potatoes.  It  is  unfortunate  that  so  little 
attention  has  been  paid  to  hay  crops  in  the  United  States 
compared  with  that  given  to  the  inter-tilled  crops  and 
to  the  grains.     Tillage,  manure,  fertilizer  and  care  are 


104  The  Potato 

too  much  concentrated  on  the  other  crops  of  a  rotation 
and  the  hay  is  left  to  grow  as  best  it  can.  The  handling 
of  meadows  and  pastures  is  far  better  understood  in 
Europe  than  in  America,  some  being  hundreds  of  years 
old.  The  use  of  better  seed  mixtures,  of  better  methods 
of  seeding,  of  better  adaptation  of  the  different  hay  crops 
to  soils  and  of  better  fertilization  will  not  only  add  directly 
to  the  yield  and  value  of  hay  crops,  but  will  increase 
greatly  the  yields  of  the  other  crops  of  any  rotation  by 
increasing  soil  fertility. 

The  statement  is  often  made  that  when  farm  crops  are 
fed  to  animals,  the  entire  crop  is  returned  to  the  soil  in 
the  manure.  This  is  nearly  true  in  regard  to  the  mineral 
elements  when  the  manure  is  well  cared  for.  But  the 
organic  matter  is  very  largely  lost  in  the  process  of  diges- 
tion. Over  sixty  per  cent  of  that  of  hay  and  straw  is 
used  in  this  way,  somewhat  less  in  the  case  of  grain  feeds. 
In  addition  there  is  the  loss  in  the  handling  of  the  manure. 
While  the  remainder  is  in  more  quickly  available  condi- 
tion than  in  straw  or  in  stubble,  the  question  of  whether 
to  harvest  the  crop  to  feed  or  to  return  directly  to  the 
land  will  depend  on  the  profit  expected  from  feeding,  the 
need  of  the  soil  for  organic  matter,  the  cost  of  labor  and 
the  effect  which  either  practice  will  have  on  carrying  out 
the  rotation  in  use.  The  millions  of  people  in  cities  must 
be  fed.  The  organic  matter  and  mineral  plant-food  in 
the  produce  shipped  is  lost  to  the  farm,  but  other  means 
can  be  found  of  replacing  both.  The  price  of  farm  prod- 
uce within  easy  shipping  distance  of  cities  is  often  greater 
than  its  value  as  feed  for  animals  on  the  farm.  Under 
these  conditions  it  pays  to  sell  crops  and  keep  up  soil 
fertility  by  fertilizers,  catch-crops,  and  by  attention  to 
increasing  crop  residues  left  in  the  soil.  '  Prices  for  farm 


Climate,  Soils  and  Rotation  105 

produce  are  now  high  enough  so  that  this  can  be  done. 
The  great  danger  which  the  history  of  American  farming 
has  shown  is  that  the  temptation  to  sell  off  cash  crops 
too  closely  is  so  great  that  attention  to  maintaining  fer- 
tility is  put  off  too  long.  Animal  husbandry  has  the 
advantage  in  practice  that  the  return  of  the  manure  to  the 
soil  is  a  necessary  part  of  farm  work  and  soil  robbery  is 
less  likely  to  result. 

The  third  way  to  return  organic  matter  to  the  soil  is 
to  return  the  entire  product  of  any  crop.  Any  crop  may 
be  used  for  this  purpose,  although,  in  practice,  those  used 
are  usually  of  low  cash  value.  Great  need  of  soil  organic 
matter  and  increase  in  yield  incident  to  such  a  valuable 
cash  crop  as  the  potato  may  make  it  advisable  to  plow 
under  crops  like  clover  which  would  be  inadvisable  in 
other  crop  rotations  of  less  value.  The  term  "green- 
manure"  refers  to  crops  plowed  under  before  maturity. 
The  term  "catch-crop"  refers  to  one  grown  between 
crops  raised  for  sale  or  feed  or  for  other  uses.  The  term 
"cover-crop"  is  usually  restricted  to  those  grown  to 
occupy  the  soil  during  the  winter.  In  addition  to  supply- 
ing organic  matter,  any  of  these  may  cover  and  protect 
the  soil  and  so  prevent  losses  by  erosion  and  leaching. 
A  crop  plowed  under  while  still  green  and  immature,  and 
which  contains  such  a  large  proportion  of  water  that  it 
decays  quickly,  may  give  only  a  small  net  gain  over  the 
cost  of  seed  and  planting  and  the  amount  of  organic 
matter  destroyed  by  tillage.  Green-manures  must  be 
used  with  caution  wherever  their  use  is  likely  to  reduce 
the  soil  moisture  for  the  following  crop.  Rye  plowed 
under  in  spring  is  often  injurious  in  this  way.  The 
amount  of  water  needed  for  large  crops  of  potatoes  is  so 
great  that  earlj-  spring  plowing  or  surface  tillage  is  usually 


106  The  Potato 

advisable  to  save  as  much  moisture  as  possible  for  the 
potatoes.  Another  danger  from  the  use  of  any  form  of 
organic  matter  plowed  under  shortly  before  planting  is 
that  movement  of  the  soil  water  may  be  hindered  and 
the  plants  injured  for  lack  of  it.  So  much  of  the  money 
value  of  grain  crops  is  in  the  seed  that  it  usually  pays  to 
harvest  the  crop,  sell  or  feed  the  grain  and  return  the 
stalks  or  straw  only  to  the  soil.  Many  experiments  have 
shown  that  the  amount  of  organic  matter  in  any  crop 
increases  most  rapidly  in  the  latter  part  of  its  life ;  so 
that  in  the  straw  of  a  grain  crop  there  is  likely  to  be  found 
more  than  that  in  the  wliole  crop  if  plowed  under  a  few 
weeks  before  maturity.  The  value  of  the  grain  is  several 
times  the  cost  of  harvesting  and  threshing.  The  use  of 
the  hay  crops  seeded  with  the  small  grains  to  plow  under 
gives  larger  net  returns  of  organic  matter  to  the  soil, 
because,  unlike  rye,  buckwheat,  or  soy  beans,  there  is  no 
destruction  of  organic  matter  by  tillage  in  planting. 

The  need  of  winter  cover-crops  for  soils  is  least  where 
the  ground  is  constantly  frozen  or  covered  by  snow 
throughout  the  winter.  Mild  and  open  winters,  as  in 
the  South,  make  it  desirable  to  have  the  soil  covered  by 
plants  which  will  prevent  erosion  and  save  plant-food 
which  would  otherwise  leach  away.  Unless  left  to  grow 
too  long  in  spring,  there  is  little  danger  in  humid  sections 
of  loss  of  enough  water  to  injure  later  money-crops  like 
potatoes. 

The  choice  of  catch-,  cover-  and  green-manure-crops 
for  any  particular  rotation,  soil  and  climate  depends  on 
many  factors  which  differ  from  those  governing  the  choice 
of  the  money-crops  of  the  rotation  only  because  cover- 
crops  seldom  have  a  cash  value.  Those  crops  of  any 
rotation  which  have  the  greatest  value,  as  is  generally  the 


Climate,  Soils  and  Rotation  107 

case  with  potatoes,  naturally  govern  the  choice  of  others 
to  a  great  extent.  The  degree  of  its  adaptability  to  soil 
and  climate,  ability  to  fit  into  rotation  with  other  crops, 
money  value,  net  increase  or  decrease  in  soil  fertility,  and 
cost  of  growing  are  all  to  be  considered. 

ROTATION 

It  is  seldom  desirable  to  grow  the  potato  continuously 
on  the  same  soil.  The  reasons  for  the  rotation  of  the 
potato  with  other  crops  are :  (1)  Plant  diseases  often 
rapidly  become  worse  when  crops  are  grown  continuously. 
This  has  often  been  the  case  with  the  potato.  Modern 
scientific  methods  of  care  of  seed,  selection,  disinfection, 
spraying  and  other  details  of  culture  somewhat  reduce 
this  danger.  (2)  In  the  business  management  of  the 
farm,  rotation  reduces  the  danger  of  excessive  losses  in 
seasons  of  low  prices  or  of  poor  yields,  and  arranges  the 
work  of  the  farm  through  the  season  to  better  advantage. 
(3)  Weeds  are  easier  controlled  under  a  system  of  rota- 
tion. Those  which  flourish  under  the  conditions  of 
growth  of  one  crop  may  be  easily  kept  down  under  an- 
other. The  high  value  of  the  potato  crop  pays  for 
thorough  tillage  and  care  which  cleans  the  soil  of  weeds 
for  the  rest  of  the  rotation.  (4)  Insect  pests  are  kept 
down  easier  under  rotation.  (5)  The  high  cash  value  of 
potatoes  justifies  considerable  sums  of  money  spent  on 
fertilizers  and  enables  more  of  the  time  of  the  rotation 
to  be  used  in  producing  organic  matter  to  be  returned 
later  to  the  soil.  The  thorough  culture,  late  digging  and 
winter  exposure  of  soil  after  potatoes  in  the  northern 
states  rapidly  uses  up  the  soil  organic  matter.  The 
cheapest  and  easiest  way  of  replacement  is  by  rotation 


108  The  Potato 

with  grass,  clover  and  other  hay  crops  which  have  a  money 
vakie  as  food  for  animals,  and  also  leave  large  amounts 
of  organic  matter  in  the  soil  from  their  roots  and  stubble, 
as  well  as  that  in  the  manure  from  the  hay  fed.  Legumes 
are  able  to  draw  part  of  their  nitrogen  from  the  air  to 
increase  the  soil  supply.  Some  nitrogen  is  also  obtained 
from  the  air  in  other  ways,  as  by  the  non-symbiotic 
bacteria.  This  is  shown  by  the  great  fertility  of  the  wild 
prairie  soils  which  have  had  few  leguminous  plants. 
(G)  Different  plants  draw  on  the  plant-food  in  the  soil 
in  varying  proportions.  Consequently  a  rotation  of  crops 
enables  each  to  secure  its  plant-food  easier  than  it  would 
if  grown  continuously.  (7)  Though  the  potato  sends  its 
roots  deeper  than  some  crops,  there  are  others,  like  clover 
and  alfalfa,  which  root  much  deeper.  These  bring  up 
fertility  from  the  subsoil,  and  the  roots  of  potatoes  follow- 
ing are  able  to  grow  lower,  even  in  hard  clay  soils. ^  (8)  It 
is  believed  that  plants  throw  off  in  the  soil  in  their  growth 
toxic  substances  which  by  accumulation  become  injurious 
to  succeeding  crops  of  the  same  plant  but  not  to  others. 
(9)  The  physical  condition  of  the  soil  for  succeeding  crops 
is  improved  by  the  thorough  culture  given  the  potato. 
Instances  of  this  are  the  use  of  wheat  following  potatoes 
without  plowing  in  fall,  and  oats  without  plowing  in 
spring. 

The  net  return  of  the  rotation  as  a  whole  must  be  the 
deciding  factor  in  the  choice  of  crops.  The  potato  gives 
such  large  cash  returns  to  the  acre  and  responds  so  well 
to  the  use  of  fertilizers  that  it  is  usually  the  most  important 
crop  of  the  rotation  in  which  it  is  grown.  Wherever  this 
is  true,  the  choice  of  the  other  crops  to  go  with  it  is  largely 
governed  by  their  effect  on  the  soil  for  the  production  of 

1  Colo.  Bui.  216. 


Climate,  Soils  and  Rotation.  109 

the  potato.  In  the  northeastern  states  the  most  common 
rotation  is  one  of  a  tilled  crop  like  potatoes  or  corn  the 
first  year,  a  small  grain  crop  usually  oats  or  wheat  the 
second  year,  in  which  grass  seeds  are  sown.  In  regions 
of  the  most  intensive  culture,  this  hay  crop  is  cut  only 
one  year  and  in  that  case  it  is  clover.  In  others  the  mix- 
ture is  clover  and  timothy  with  occasionally  redtop,  which 
is  cut  several  years.  Further  South,  where  grasses  do 
not  grow  well,  it  is  necessary  to  use  annual  hay  crops  like 
crimson  clover  or  cowpeas.  In  the  North  grass  seeds 
are  seldom  sown  alone.  The  practice  of  summer  tillage 
before  sowing  alfalfa  has  been  found  so  valuable  that  it  is 
coming  into  use  for  the  sowing  of  the  grasses  as  well, 
particularly  on  weedy  soils,  or  on  those  on  which  it  is 
difficult  to  get  seeds  sown  with  grain  to  catch. 

The  relative  profit  to  be  expected  from  the  growth  of 
potatoes,  grain  and  hay  determines  the  number  of  years 
which  each  will  use  in  a  given  rotation  for  any  locality. 
In  New  England  hay  and  potatoes  are  both  relatively 
more  valuable  than  grain,  and  each  may  occupy  the  soil 
for  two  years  out  of  a  five-year  rotation.  In  New  York 
and  Pennsylvania  the  hay  may  be  cut  for  several  years. 
Going  South,  hay  is  grown  less  and  less  until  in  the  truck- 
ing section  potatoes  are  rotated  mainly  with  other  truck 
crops  as  spinach  and  cabbage.  In  the  middle  West  the 
higher  cost  of  transportation  of  potatoes  and  hay  com- 
pared with  grain  causes  the  latter  to  be  grown  several 
years  in  a  rotation,  as  is  often  the  case  in  the  Red  River 
section. 

Hay  plants 

Alfalfa  is  the  best  crop  to  rotate  with  potatoes  where 
it  can  be  grown  with  profit,  as  in  the  Rocky  Mountain 


110  The  Potato 

region.  It  is  a  perennial,  is  deep-rooted,  produces  several 
cuttings  to  distribute  labor  and  risk  of  bad  weather 
through  a  longer  period,  yields  heavily,  is  of  high  value 
for  either  feed  or  sale,  gets  part  of  its  nitrogen  from  the 
air  and  part  of  its  mineral  food  from  the  deep  subsoil, 
and  leaves  the  soil  in  excellent  condition  to  grow  potatoes. 
Its  use  is  gradually  extending  in  the  eastern  half  of  the 
United  States  as  the  methods  necessary  for  its  growth 
become  better  understood.  It  may  never  attain  to  the 
commanding  position  here  which  it  holds  in  the  agricul- 
ture of  the  western  half  of  the  country,  but  it  is  certain 
to  become  more  generally  grown  than  now.  An  objec- 
tion to  the  use  of  alfalfa  in  a  potato  rotation  in  the  East 
is  that  the  heavy  liming  generally  necessary  induces  scab 
on  the  potatoes. 

The  hay  crops  usually  grown  in  rotation  with  potatoes 
in  the  northern  states  are  the  clovers,  timothy  and  red- 
top.  Except  for  growing  only  one  season,  red  clover  has 
most  of  the  good  qualities  of  alfalfa.  The  growth  of 
either  is  a  sign  of  land  in  good  condition.  Both  require 
considerable  lime  in  the  soil,  though  clover  needs  less 
than  alfalfa.  While  the  potato  will  make  fair  crops  on 
land  that  is  sour  and  low  in  organic  matter,  it  grows 
better  if  the  soil  is  in  the  well-drained  and  slightly  alkaline 
condition  in  which  the  beneficial  soil  bacteria  live  best. 
The  second  cutting  of  common  red  clover  is  often  turned 
under  in  potato  rotations  on  account  of  benefit  to  the  soil. 
Mammoth  red  clover  is  a  larger  and  coarser  variety  of 
the  red.  Alsike  clover  is  lighter  in  yield  than  the  red,  but 
is  able  to  grow  on  many  poor,  wet  or  sour  soils  where  red 
clover  will  fail.  It  should  be  substituted  for  the  red 
wholly  or  in  part  wherever  there  is  danger  that  the  red 
will  fail  to  grow.     Timothy  is  a  hay  plant  of  great  value 


Climate,  Soils  and  Rotation  111 

when  handled  correctly.  It  will  grow  on  many  soils,  fur- 
nishes a  fairly  heavy  root  system  and  stubble  to  keep  up 
soil  organic  matter,  gives  a  good  yield  of  hay  which  is 
easily  cured  and  finds  ready  sale  at  good  prices  for  horse 
feeding.  The  close  sod  formed  by  timothy  prevents 
erosion  and  helps  to  keep  weeds  down.  The  use  of  lime, 
manure  and  fertilizers  on  timothy  greatly  increases  the 
yield  and  keeps  it  longer  at  a  high  production.  A  very 
common  fault  in  the  handling  of  timothy  is  to  let  it  stand 
so  long  that  many  plants  die  out  and  when  the  remainder 
are  turned  under  there  is  but  little  organic  matter  to 
supply  succeeding  crops.  It  should  be  plowed  while 
there  is  yet  material  to  enrich  the  soil.  Redtop  is  a  hay 
plant  seldom  appreciated  outside  of  New  England.  A 
prejudice  against  redtop  in  mixture  in  market  hay  re- 
duces the  price  on  account  of  a  common  practice  of  letting 
it  stand  until  woody  before  cutting.  Properly  handled, 
its  value  for  feeding  is  practically  that  of  timothy.  By 
the  well-known  principle  that  a  mixture  of  grasses  yields 
better  than  either  alone,  redtop  increases  the  yield  of 
mixtures  in  which  it  is  included  and  is  particularly  valu- 
able for  humus  production  on  account  of  its  very  heavy 
sod.     It  grows  in  soils  too  poor,  wet  or  dry  for  timothy. 

The  selection  of  the  hay  plants  to  be  grown  in  any  rota- 
tion with  potatoes  should  be  carefully  considered  with 
the  idea  of  building  up  soil  fertility  as  well  as  producing 
hay  for  feeding  or  sale.  Alfalfa,  red  clover,  alsike  clover, 
timothy  and  redtop  require  for  their  growth  soils  varying 
in  fertility,  drainage  and  lime  content  in  about  the  order 
named.  Potatoes  should  be  rotated  with  alfalfa  where  it 
succeeds.  In  all  others,  and  this  includes  nearly  all  the 
northern  and  eastern  states  from  the  Red  River  to  Maine, 
the  capacity  of  the  soil  determines  whether  red  clover 


112  The  Potato 

should  be  sown  alone,  or  another  mixture.  This  might 
be  red  and  alsike  clover,  the  clovers  with  timothy  or  both 
timothy  and  redtop,  or  perhaps  on  some  of  the  poorer 
volusia  soils  and  others  of  that  low  grade  of  fertility,  red 
clover  is  best  left  out  unless  limed  and  only  alsike,  timothy 
and  redtop  sown. 

In  southern  sections  there  is  difficulty  in  growing  the 
northern  hay  plants  mentioned.  Reliance  must  be  placed 
on  annuals  for  most  of  the  hay  and  for  cover-crops. 
Crimson  clover,  wheat,  rye,  winter  oats,  hairy  vetch,  soy- 
beans, cowpeas,  peanuts  and  velvet  beans  are  used  in  the 
southern  states  for  these  purposes. 

In  the  West  where  irrigation  is  practiced,  alfalfa  is 
used  more  than  any  other  crop  to  rotate  with  potatoes  to 
supply  organic  matter.     Field  peas  are  also  used. 

REFERENCES 

Agee.     Crops  and  Methods  for  Soil  Improvement. 

Brooks.     Agriculture,  Vol.  I,  Soils. 

Eraser.     The  Potato. 

Grubb  and  Guh^foAd.     The  Potato. 

Terry.     The  A.  B.  C.  of  Potato  Culture. 

Bui.  87,  Bur.  PI.  Ind.,  U.  S.  Dept.  Agr.  Authority  for  "  Critical 

Period,"  p.  96. 
Bui.  49,  Can.  Central  Exp.  Farms,  Effect  of  Heat  on  Seed  Vitality. 
Buls.  347,  352,  397  N.  Y.  (Geneva)  Exp.  Sta.,  and  Bui.  159,  Vt. 

Exp.  Sta.,  On  Effect  of  Spraying  in  Dry  Season. 


CHAPTER  VI 

MANURES  AND  FERTILIZERS 

By  Daniel  Dean 

The  supply  of  plant-food  elements  present  in  soils  will 
produce  potato  crops  of  varying  size  according  to  the 
climate,  the  original  natural  fertility  of  the  soil-type  and 
the  degree  to  which  it  has  been  reduced  or  improved  in 
condition  since  bringing  under  cultivation.  Manures  and 
fertilizers  are  used  to  add  plant-food  in  forms  so  easily  and 
quickly  available  that  the  crop  wull  be  able  to  take  up 
and  use  more  than  it  could  without  them.  On  account 
of  its  tender  nature,  compared  with  other  farm  crops,  the 
potato  responds  well  to  the  use  of  fertilizers.  Manures 
and  fertilizers  are  used  wherever  the  increased  yield  brings 
enough  in  the  market  returns  to  meet  the  additional  cost 
and  leave  a  profit.  For  these  reasons,  the  use  of  fertilizers 
is  more  or  less  localized  in  the  particular  sections  where 
their  use  is  most  profitable.  For  example,  the  cool  and 
moist  climate  of  the  Aroostook  region  of  Maine  is  very  fa- 
vorable to  the  production  of  large  yields  of  potatoes  to  the 
acre.  In  spite  of  the  great  natural  fertility  of  the  soils, 
these  fertilizers  are  used  to  the  extent  of  over  1900  pounds 
to  the  acre  on  the  average  at  a  cost  of  over  $30,  because 
the  practice  pays.  The  great  trucking  region  which 
supplies  city  markets  from  April  till  autumn  and  extends 
along  the  Atlantic  coast  from  Florida  to  Long  Island  is 
nearly  all  made  up  of  sandy  soils  of  low  natural  fertility. 
I  113 


114  The  Potato 

The  comparatively  higli  prices  received  for  this  early  crop 
makes  heavy  fertilizing,  often  over  2000  pounds  to  the 
acre,  profitable.  By  contrast,  the  irrigated  sections  of 
the  Rocky  INIountain  region  often  have  soils  very  rich  in 
the  mineral  plant-food  elements.  Though  often  low  in  the 
supph'  of  nitrogen,  this  is  obtained  by  rotating  the  potato 
crop  with  alfalfa.  This  would  render  fertilizers  of  little 
value  for  these  conditions  even  if  the  high  freight  costs 
from  our  present  sources  of  supply  did  not  put  fertilizers 
out  of  the  question. 

Scientists  are  not  fully  agreed  as  to  the  functions  of  the 
different  elements  in  the  soil  used  by  plants.  Experiments 
have  proved  that  several  must  be  present  or  plants  will 
not  grow.  The  common  term  "plant-food"  is  applied 
from  these  experiments.  Fertilizers  have  other  actions 
of  value  to  plants,  some  well  understood,  and  some  which 
have  only  been  discovered  and  are  as  yet  not  very  well 
known.  One  is  their  favorable  action  on  the  beneficial 
bacteria  present  in  the  soil.^  Certain  fertilizers,  by  ren- 
dering soil  conditions  more  favorable  for  them,  increase 
indirectly  the  fertility  of  the  soil  as  well  as  by  their  direct 
action.  Our  knowledge  of  these  bacteria  is  limited  at 
present  in  some  directions,  but  it  is  certain  that  their 
importance  to  agriculture  is  very  great,  much  greater  than 
is  generally  known.  One  limit  to  the  yield  of  farm  crops 
is  the  amount  of  water  which  is  available  for  their  use. 
This  is  shown  by  the  great  gains  from  the  practice  of  irri- 
gation. Fertilizers  practically  increase  the  water  supply 
by  increasing  the  concentration  of  the  solution  of  plant- 
foods  in  the  soil  water  and  so  enable  the  plants  to  secure 
more  from  the  same  amount  of  water  in  the  soil.- 

1  Office  of  Expt.  Sta.,  Bui.  194. 

«  U.  S.  D.  A.,  Bureau  of  Soils,  Bui.  22. 


Manures  and  Fertilizers  115 

It  is  thought  that  to  some  extent  fertihzers  act  as  disin- 
fectants to  reduce  damage  by  unfavorable  agents  in  the  soil. 

FERTILIZER   PRACTICES 

Elements  often  present  in  the  soil  in  too  small  quantities 
for  the  best  growth  are  nitrogen,  phosphorus,  potassium 
and  calcium.  Wlien  these  are  added  in  the  form  of  fer- 
tilizers or  manure,  the  yield  of  most  crops  is  increased. 
The  extent  to  which  farmers  may  use  fertilizers  depends 
on  the  cost  of  the  fertilizer  compared  with  the  net  value  of 
the  increase  in  the  crop.  Another  factor  which  must  be 
considered  is  the  residual  effect  of  fertilizers  on  the  soil. 
In  the  early  days  of  the  use  of  fertilizers,  small  applications 
were  often  made  without  much  attempt  to  maintain  the 
soil  supply  of  organic  matter.  When  the  amount  supplied 
was  sufficient  only  to  give  the  young  plant  a  better  start, 
it  is  probable  that  the  increase  in  yield  removed  more  of 
the  plant-food  elements  than  was  added  in  the  fertilizers. 
Being  usually  applied  to  grain  or  to  tilled  crops,  there 
was  but  little  increase  in  the  amount  of  organic  matter 
returned  to  the  soil  in  the  plant  residues,  not  enough  to 
replace  that  destroyed  by  the  processes  of  tillage.  This 
has  led  to  a  strong  belief  among  older  farmers  that  "  fer- 
tilizers will  run  out  the  soil."  The  present  tendency 
among  potato-growers  is  to  use  much  larger  applications, 
which  supply  an  excess  of  soluble  plant-food  elements 
over  those  removed  in  the  crop. 

Practice  in  the  use  of  fertilizers  was  for  many  years 
based  on  the  theories  of  the  famous  German  chemist  Von 
Liebig.  He  taught  that  plant-food  must  be  returned  to 
any  soil  to  equal  exactly  that  removed  in  the  crop.  The 
practical  error  in  the  assumption  that  the  composition 


116  TJw  Potato 

of  a  fertilizer  for  any  crop  is  determined  by  the  chemical 
analysis  of  the  crop  itself  is  that  it  does  not  sufficiently 
take  into  account  the  great  natural  stores  of  plant-food 
in  the  soil,  nor  the  biological  conditions.  The  plant-food 
needs  of  the  growing  plant  at  any  time  are  not  necessarily 
based  on  its  final  composition.  The  presence  of  a  par- 
ticular number  of  pounds  of  an  element  in  soluble  form 
somewhere  among  the  millions  of  pounds  of  soil  on  an 
acre  is  no  guarantee  that  the  plant  roots  will  be  able  to 
find  and  use  it  at  the  time  when  it  is  most  needed. 

Growers  in  specialized  potato-growing  regions  like  Aroos- 
took County  and  the  early  truck  potato  section  apply  more 
plant-food  than  the  potato  can  be  expected  to  remove  in 
the  crop,  in  order  to  make  certain  that  it  will  not  have  to 
suffer  for  a  lack  at  any  time.  The  effect  of  this  practice 
is  seen  in  the  subsequent  crops.  In  southern  trucking 
regions,  the  choice  of  the  crop  to  follow  heavily  fertilized 
potatoes  is  largely  governed  by  its  ability  to  make  good 
use  of  the  fertilizer  left  by  the  potatoes.  The  longer  ex- 
perience of  European  farmers  with  fertilizers  has  resulted 
in  England  in  laws  by  which  the  value  of  the  fertilizers  left 
in  a  soil  by  crops  is  computed.  Under  the  tenant  system, 
by  which  most  of  the  farms  of  England  are  worked,  an 
outgoing  tenant  must  be  paid  by  his  successor  for  the 
unused  fertilizer  left.  This  proportion  of  the  value  of  the 
fertilizers  applied  varies  with  different  materials,  being 
lowest  with  the  soluble  nitrate  of  soda  and  highest  with 
such  slowly  acting  materials  as  ground  bone  and  lime. 

MARKET    FORMS    OF    FERTILIZERS 

Commercial  fertilizers  are  found  on  the  market  in  the 
form  of  manv  different  materials  which  are  also  manu- 


Manures  and  Fertilizers  117 

factiired  into  many  branda  of  mixed  fertilizers,  usually 
being  prepared  for  some  special  crop  or  soil.  Both  the 
materials  and  mixed  fertilizers  are  sold  under  statement 
of  definite  percentages  of  the  plant-foods  they  contain. 
Annual  state  inspection  and  analysis  show  that  these 
statements  are  usually  reliable.  Each  has  advantages 
for  farmers'  use.  The  mixed  factory  goods  are  usually 
in  good  mechanical  condition  for  sowing  and  are  generally 
kept  or  can  be  soon  obtained  from  dealers.  These  dealers 
usually  extend  credit  to  buyers.  The  manufacturers 
contend  that  by  the  wet  or  acid  process  they  are  liable  to 
utilize  materials  too  insoluble  for  use  directly  by  crops. 
The  many  trade  brands  for  the  same  crop  may  differ 
greatly  in  composition ;  and  often  a  number  of  brands 
having  the  same  analysis  are  sold  as  "special  fertilizers" 
for  widely  varying  crops. 

The  variation  between  soils  is  so  great  that  the  same 
crop  raised  on  different  lands  may  require  widely  varying 
fertilizers  for  the  best  results.  Only  experience  and  careful 
study  will  show  what  these  requirements  are.  Such  study 
and  observation  are  rather  rare  in  America.  In  Europe, 
farmers  are  more  accustomed  carefully  to  mix  their  ferti- 
lizers according  to  the  special  needs  of  each  combination  of 
soil  and  crop.  In  Germany  this  goes  so  far  that  the  mate- 
rials are  often  applied  separately  at  the  most  favorable  time 
for  the  action  of  each,  although  this  would  not  be  advisable 
here  on  account  of  greater  cost  of  labor.  The  materials 
used  by  farmers  in  home  mixtures  are  usually  of  high  grade. 
Sometimes,  as  with  nitrate  of  soda,  acid  phosphate  and  muri- 
ate of  potash,  a  mixture  that  is  of  the  right  analysis  for  a 
particular  crop  may  be  composed  of  materials  that  are 
sticky  in  combination  and  do  not  drill  well.  Care  must 
often  be  taken  to  include  materials  like  dried  blood,  tank- 


118  The  Potato 

age,  ground  bone  and  sulphate  of  ammonia  that  drill  well. 
The  cost  of  home  mixing  may  be  one  dollar  a  ton,  more  or 
less,  sometimes  under  fifty  cents.  A  tight  wagon  box  or 
barn  floor,  screen,  measure  and  shovel  are  the  only  belong- 
ings needed  if  enough  is  mixed  so  that  batches  are  made 
up  of  one  or  more  bags  of  each  material.  If  less,  scales 
are  needed.  Dealers  do  not  like  to  sell  materials  in  small 
quantities,  but  by  clubbing  together  farmers  can  buy  car- 
load lots. 

Most  of  the  phosphoric  acid  in  factory-mixed  fertilizers 
comes  from  acid  phosphate.  The  value  is  the  same  from 
any  source  if  acid  treated.  If  not  so  treated,  as  in  tankage 
or  ground  bone,  it  is  slower  to  become  available.  IVIost  of 
the  potash  comes  from  muriate  and  kainit,  which  differ  but 
little  in  their  action  ;  some  comes  from  sulphate.  Fertil- 
izers vary  mostly  in  the  value  of  the  nitrogen.  The  higher- 
grade  factory-mixed  fertilizers  are  more  certain  to  have 
high-grade  nitrogen  than  the  low-grade  cheaper  mixtures. 

Before  the  great  European  war,  the  prices  of  fertilizers 
had  remained  fairly  constant  for  a  number  of  years.  The 
experiment  stations  in  the  northeastern  states  usually 
value  the  best  grades  of  nitrogen  at  15  to  18  cents  a  pound, 
soluble  phosphoric  acid  in  acid  phosphate  and  potash  in 
muriate  at  about  5  cents.  These  prices  are  ton  lots  of 
the  best  materials  bought  for  cash  in  large  markets. 
Buyers  of  car-lots  usually  purchase  enough  cheaper  to 
cover  the  cost  of  freight  to  country  points  at  these  prices. 

Lack  of  knowledge  of  fertilizers  among  farmers  has  led 
to  a  failure  to  appreciate  the  fact  that  it  is  the  cost  a  pound 
of  the  plant-food  which  the  fertilizer  contains  and  its 
quality  that  determines  the  actual  value  of  any  fertilizer, 
not  the  price  a  ton.  Many  farmers  look  too  often  at 
the  cheapest,  regardless  of  the  analysis.     For  example, 


Manures  and  Fertilizers  119 

muriate  of  potash  contains  four  times  as  much  potash 
in  a  ton  as  kainit  and  often  costs  less  for  the  one  ton  than 
for  four  tons  of  the  less  concentrated  material,  making 
the  potash  cost  less  a  pound,  in  addition  to  the  saving 
in  labor  of  hauling  and  applying.  The  cost  a  pound  of 
nitrogen  in  high-grade  dried  blood,  nitrate  of  soda  and 
sulphate  of  ammonia  at  $50  to  $70  a  ton,  may  be  less  than 
in  the  cheaper  grades  of  tankage  and  the  like,  besides 
being  of  far  better  quality. 

There  is  less  variation  in  the  price  a  ton  of  acid  phos- 
phates because  the  best  sold  in  America  seldom  exceeds 
16  per  cent.  The  relative  cheapness  of  plant-food  in 
mixed  fertilizers  depends  largely  on  the  analysis. 

Mixtures  of  acid  phosphate  and  potash  are  compara- 
tively low  priced  and  at  the  same  time  are  of  high  grade 
and  cheap  for  the  amount  of  plant-food  which  they  con- 
tain. Nitrogen  is  so  expensive  that  a  small  percentage 
runs  the  price  up  rapidly.  Usually  the  higher  grades  of 
so-called  "complete  fertilizers,"  costing  $30  a  ton  or  more, 
are  relatively  cheaper  than  lower  grades  selling  around 
$20  a  ton.  It  is  usual  for  the  makers  of  the  higher-priced 
complete  fertilizers  to  claim  that  the  nitrogen  in  them  is 
in  a  variety  of  forms  of  varying  quickness  of  solubility, 
thereby  becoming  gradually  available  to  the  crop  through 
the  growing  season.  This  is  something  which  should  be 
considered  by  farmers  in  making  up  their  orders  for 
material  for  home  mixing. 

NITROGEN 

Nitrogen  helps  rapidly  to  increase  vegetative  growth. 
When  nitrogenous  fertilizers  are  extensively  used,  the 
foliage   grows   large    and    rank   and    has   a  dark    green 


120  The  Potato 

color.  In  extreme  cases  the  foliage  may  become  too  loose 
and  open  and  porous  in  texture,  and  so  render  the  potato 
plant  more  liable  to  the  attacks  of  disease  and  sun-scald. 
Lack  of  available  nitrogen  for  the  plant  is  shown  by  small 
size  and  light  yellow  color  of  the  foliage.  Commercially, 
nitrogen  used  in  fertilizers  comes  from  a  variety  of  sources 
which  vary  greatly  in  value  and  in  the  quickness  with 
which  they  become  available.  Nitrate  nitrogen,  the  form 
to  which  other  forms  must  be  changed  in  the  soil  before 
the  plants  can  take  it  up  in  the  soil  solution,  is  the  quickest 
available.  Nitrate  of  soda  is  the  principal  commercial 
form.  It  comes  from  deposits  in  Chile,  hence  the  old 
name  of  "Chile  saltpeter."  It  is  so  rapidly  soluble  in 
water  that  it  may  sometimes  be  dissolved  and  lost  to  the 
plant  if  heavy  rains  fall  before  the  feeding  roots  have  had 
time  to  form.  For  this  reason,  it  is  either  applied  after 
planting  as  a  top-dressing  or  is  used  foi"  only  a  part  of 
the  nitrogen  of  a  mixture,  the  remainder  being  in  slower 
acting  forms.  Because  of  this  rapidity  of  action,  nitrate 
of  soda  is  particularly  valuable  for  use  in  early  spring,  on 
early  potatoes  before  the  soil  warms  up  enough  for  the 
processes  by  which  the  other  forms  of  nitrogen  change  to 
nitrate.  It  contains  about  15  per  cent  of  nitrogen.  Sul- 
phate of  ammonia,  a  by-product  of  coke  and  gas  manu- 
facture from  coal,  is  next  in  order  of  availability.  It 
contains  the  largest  percentage  of  nitrogen  of  any  material 
—  20  per  cent.  It  has  good  mechanical  condition  for 
mixing  or  sowing.  One  drawback  is  that  its  use  tends  to 
make  land  sour  and  that  it  is  not  very  efficient  on  sour 
soils.  Nitrate  of  lime  and  cyanamid  are  comparatively 
new  commodities,  being  made  from  the  gaseous  nitrogen 
of  the  air  by  the  use  of  electricity.  While  not  extensively 
used,  it  is  probable  that  in  time  they  will  become  very 


Manures  and  Fertilizers  121 

important  sources  of  nitrogen.  Cyanamid  is  difficult  to 
mix  well  in  fertilizers  and  has  other  drawbacks. 

Much  of  the  nitrogen  of  factory-mixed  fertilizers  comes 
from  organic  sources.  These  are  slower  in  their  action, 
as  the  organic  forms  of  nitrogen  must  be  changed  first  to 
ammonia  and  then  to  nitrate  before  the  plants  can  take 
them  up.  Warm  weather  and  warm  soil  are  needed  for  this. 
Dried  blood  is  the  best  of  the  organic  forms,  with  tankage, 
fish  scrap  and  cottonseed  meal  also  used  in  different  sec- 
tions. Other  more  slowly  available  forms  like  leather, 
animal  bone  and  horn  meal  are  nearly  useless  to  the 
potato  crop  unless  treated  with  acid  by  the  wet  process  to 
make  them  more  soluble.  In  comparing  the  prices  of  any 
of  these  materials,  the  degree  of  availability  must  be 
considered  as  well  as  the  price  a  pound  of  the  nitrogen. 
It  is  unfortunate  that  state  laws  do  not  compel  the  state- 
ment of  the  percentage  of  each  of  the  principal  forms  in 
which  nitrogen  is  found  in  fertilizers  as  well  as  the  total. 
At  present  the  nitrogen  in  as  poor  a  material  as  dried  peat, 
oft(m  used  as  a  drier  in  mixed  fertilizers,  counts  as  high  in 
the  total  percentage  of  nitrogen  as  from  nitrate  of  soda 
or  dried  blood. 

Nitrogen  is  so  much  more  expensive  than  the  other 
elements  of  plant-food  and  so  easily  lost  from  the  soil  that 
every  effort  should  be  made  to  conserve  and  increase  the 
soil  supply  by  the  use  of  rotations  which  provide  plenty  of 
organic  matter,  including  legumes,  and  by  making  soil 
conditions  as  favorable  as  possible  for  the  different  soil 
bacteria  which  take  or  change  nitrogen.  The  other  plant- 
foods  are  in  the  soil  in  stable  forms  which  are  not  easily 
lost.  Nitrogen  exists  largely  in  very  unstable  forms  which 
are  easily  lost  in  drainage  water  or  b}'^  changing  into  the 
gaseous  form  of  nitrogen. 


122  The  Potato 


PHOSPHORUS 


Phosphorus,  usually  referred  to  under  the  name  of  its 
form  as  phosphoric  acid,  or  P2O5,  is  often  in  very  small 
quantities  in  American  soils,  even  in  those  abundantly 
supplied  with  other  elements  of  plant-food.^  Its  actions 
on  growth  are  not  fully  understood,  but  are  very  im- 
portant and  are  becoming  more  and  more  appreciated. 
A  deficiency  in  soluble  phosphoric  acid  quickly  reduces  a 
crop  yield.  Unless  a  sufficient  amount  is  present,  plants 
do  not  mature  properly.  Its  use  tends  to  produce  early 
maturity  and  is  marked  by  dark  green  foliage. 

The  principal  supply  for  use  in  fertilizers  comes  from 
deposits  in  the  South  which  are  supposed  to  be  derived 
from  fossil  bones.  When  ground  finely,  this  material  is 
sold  under  the  name  of  "floats"  or  "raw  rock  phosphate." 
It  is  much  used  in  the  corn  belt  states  and  gives  good 
results  there  on  general  farm  crops.  It  is  too  slow- 
acting  for  the  more  delicate  potato  crop,  and  has  not  given 
very  good  results  in  most  experiments  in  the  colder  north- 
eastern states.  Acid  phosphate  is  made  by  treating  this 
raw  rock  phosphate  with  sulphuric  acid.  This  unites  with 
part  of  the  lime  in  natural  coml)inations  with  phosphoric 
acid.  Instead  of  the  insoluble  jjhosphate  in  which  three 
parts  of  lime  are  united  to  each  part  of  phosphoric  acid, 
there  is  formed  the  water-soluble  form  in  which  only  one 
part  of  phosphoric  acid  is  united  to  each  part  of  lime,  to- 
gether with  a  small  proportion  of  the  reverted  form  soluble 
in  weak  soil  acids  in  which  two  parts  of  lime  are  united 
to  each  part  of  phosphoric  acid.  The  sum  of  these  makes 
up  the  available  r205.  Acid  phosphate  is  also  made  from 
animal  bones,  but  the  supply  is  only  enough  for  a  small 

'  See  Bulletins  by  Hopkins,  111.  Agri.  Expt.  Sta. 


Manures  and  Fertilizers  123 

fraction  of  all  that  is  used.  Acid  phosphate  is  the  prin- 
cipal source  of  phosphoric  acid  in  this  country,  either  for 
factory-mixed  fertilizers  or  for  home  mixing.  The  word 
"acid"  has  created  a  foolish  prejudice  against  its  use  which 
is  not  warranted  by  facts.  A  very  small  application  of 
lime  will  prevent  any  chance  of  the  soil  becoming  sour 
from  its  use.  Ground  animal  bone  and  basic  slag  are 
valuable  sources  of  phosphoric  acid  for  some  other  crops, 
but  are  too  slow  acting  for  the  tender  potato.  Different 
grades  of  American  acid  phosphates  vary  in  the  percent- 
age of  phosphoric  acid  from  12  per  cent  to  16  per  cent  or 
more.  Only  the  highest  grades  should  usually  be  bought. 
The  price  a  pound  of  the  phosphoric  acid  applied  to  the 
land  is  the  real  cost. 

In  the  northern  states  the  price  a  pound  at  the  rail- 
road station  is  usually  less  in  the  higher  than  in  the  lower 
grades  and  in  addition  there  is  the  cost  of  hauling  to  the 
farm  and  applying  to  the  land.  Three  tons  of  1(3  per  cent 
acid  phosphate  usually  cost  less  than  four  tons  of  the 
12  per  cent  and  the  cost  of  hauling  and  sowing  the  extra 
ton  is  saved. 

POTASSIUM 

Potassium,  usually  referred  to  as  "potash"  or  K2O,  is 
present  in  large  quantities  in  most  American  soils.  Some 
of  the  very  sandy  soils  near  the  seacoast  and  the  swamp 
mucks  are  likely  to  be  deficient  in  it.  Potash  helps  in  the 
translocation  of  starch  within  the  potato  plant  and  tends 
to  lengthen  the  life  of  the  crop.  Practically  all  the  com- 
mercial supply  of  potash  comes  from  deposits  in  Germany, 
controlled  by  a  syndicate  there.  The  principal  form  used 
in  America  is  that  of  muriate  of  potash  containing  47  to  50 
per  cent  of  actual  potash.     This  is  usually  the  cheapest 


124  TJie  Potato 

form  in  which  to  buy  potash.  The  chlorine  in  the  com- 
bination with  the  potash  has  some  tendency  to  make  soils 
sour,  and  in  some  experiments  ^  has  produced  smaller  yields 
and  poorer  quality  than  when  sulphate  of  potash  was  used. 
The  latter,  47  to  49  per  cent  potash,  is  more  expensive  and 
is  but  little  used  except  for  tobacco  fertilizers.  Kainit  is  a 
raw  material  of  low  grade  (12  per  cent  potash),  and  is  rela- 
tively higher  in  price  a  pound  of  potash  contained  in  most 
places  on  account  of  the  freight  on  material  of  less  value. 
Potash  fertilizers  are  mixed  in  the  soil  after  applications 
and  are  not  likely  to  be  lost  by  leaching.  The  solutions  in 
soil  water  are  rather  caustic,  and  heavy  applications  are 
likely  to  burn  the  roots  of  plants  if  applied  close  to  the 
seed.  The  old  idea  of  mixing  fertilizers  according  to  the 
chemical  composition  of  the  crop  has  led  to  the  use  of 
fertilizers  containing  much  more  potash  than  practical 
experience  of  farmers  and  scientific  experiments  warrants. 
Mixed  fertilizers  often  contain  7  to  12  per  cent  of  potash. 
A  number  of  experiments  by  the  Geneva  and  other  agri- 
cultural experiment  stations  have  shown  that  this  is  too 
high  for  profit.  Five  per  cent  is  usually  all  that  will  pay. 
Potash  is  so  abundant  in  most  American  soils  that  nitro- 
gen and  phosphorus  are  likely  to  be  much  more  needed, 

CALCIITVI 

Calcium,  in  the  form  of  lime,  is  seldom  so  deficient  in 
American  soils  as  to  render  its  use  directly  necessary  as  a 
fertilizer  for  potatoes.  In  fact,  A^ery  heavy  yields  of  pota- 
toes are  often  grown  on  soils  too  acid  to  grow  clover.  The 
potato  seems  to  be  very  tolerant  of  acid  conditions.  Heavy 
applications  of  lime  produce  conditions  under  which  the 

1  Brooks,  Mass.  Expt.  Sta. 


Manures  and  Fertilizers  125 

common  scab  is  likely  to  injure  the  tubers.^  The 
powdery  scab  prefers  acid  soils  and  is  reduced  by  liming. 
There  are  other  reasons  which  make  the  use  of  lime  of 
great  value.  The  other  crops  of  a  potato  rotation  are 
more  likely  to  be  benefited  than  the  potato,  and  the  net 
profit  of  the  rotation  as  a  whole  must  be  considered.  The 
clover  and  grass  crops  are  the  ones  most  benefited  by  lim- 
ing, and  these  are  the  ones  that  do  most  to  maintain  the 
soil  supply  of  organic  matter.  Heavy  sods  and  other 
residues  from  hay  crops  bring  up  soil  fertility  rapidly  at 
small  cost.  In  this  way  subsequent  crops  of  potatoes  are 
benefited.  Lime  is  also  essential  for  the  action  of  the 
beneficial  soil  bacteria.  Many  American  soils  are  now 
becoming  deficient  in  lime.  Lime  should  be  added  to  soils 
in  rotation  in  which  potatoes  are  grown  to  as  large  an 
amount  as  the  soil  can  use  without  producing  scab  on  the 
tubers.  What  this  amount  will  be  can  be  found  only  by 
careful  trial  on  every  soil  and  sometimes  on  every  field. 
Some  soils  can  use  several  tons  of  limestone  to  the  acre 
without  danger,  while  500  pounds  might  be  too  much  on 
limestone  soils  or  those  in  high  condition  of  fertility. 
Burned  lime  has  been  almost  the  only  source  of  lime  for 
many  years.  Ground  limestone  is  now  coming  into  use 
very  rapidly,  and  it  is  probable  that  before  many  years  will 
entirely  displace  burned  lime  in  most  places.  It  is  much 
easier  to  apply  and  its  use  is  safer.  Burned  lime  is  thought 
by  some  to  have  a  tendency  to  use  up  the  organic  matter 
in  the  soil,  even  when  thoroughly  slaked  before  application. 
Hydrated  lime  is  too  expensive  to  compare  with  the 
others.  Any  form  of  lime  should  be  applied  to  the  crop 
in  the  rotation  which  follows  potatoes,  and  should  be 
thoroughly  harrowed  into  the  soil. 

'  Vt.  Bui.  184. 


126  The  Potato 


SULPHUR 


Sulphur  is  present  in  all  soils  and  is  not  likely  to  be 
deficient  in  any  way.  There  is  some  ground  for  the  belief 
that  part  of  the  value  of  acid  phosphate  is  due  to  the 
sulphur  contained  in  it. 


APPLYING   FERTILIZERS 

The  method  by  which  fertilizers  are  applied  to  a  soil 
often  determines  the  profit  to  be  obtained  from  their  use. 
Nitrate  of  soda  is  so  quickly  and  easily  soluble  in  the  soil- 
water  that  it  can  be  sown  on  the  surface  of  the  land  at  any 
time  with  the  certainty  that  the  first  rain  will  dissolve  it, 
or  that  it  will  quickly  dissolve  if  mixed  with  the  soil. 
Other  fertilizers  require  weeks,  months  or  even  years  to 
become  available  to  plants. 

A  gradual  evolution  is  taking  place  in  the  ideas  as  to 
the  proper  use  of  fertilizers.  In  the  earlier  days  of  their 
use,  when  the  quantity  applied  w^as  limited  to  perhaps 
100  to  200  pounds  to  the  acre,  it  was  rightly  considered  as 
only  a  starter  for  the  young  plants.  It  was  applied  to  the 
soil  close  to  the  seed,  being  often  dropped  by  hand.  The 
roots  starting  from  the  young  plants  were  certain  to  find 
a  supply  of  readily  available  plant-food  as  soon  as  they 
could  use  it.  This  would  give  a  quick  start  to  the  young 
plant,  which  would  enable  it  to  grow  more  quickly  to  a 
size  when  it  would  be  able  to  forage  for  itself.  As  the 
profits  from  the  use  of  fertilizers  became  known,  the 
amounts  gradually  increased.  About  the  same  time 
machine-planters  came  into  use.  These  applied  the 
fertilizer  in  the  form  of  a  strip  several  inches  wide  in  the 
bottom  of  the  furrow-mark.     This  wide-strip  application 


Manures  and  Fertilizers  127 

is  essential  to  prevent  root  injury.  Application  with  the 
planter  works  well  whenever  moisture  is  abundant  in 
the  soil  throughout  the  growing  season  in  Maine.  As  the 
amount  applied  to  the  acre  increased  to  1000  pounds  or 
more,  growers  began  to  use  a  wider  distribution  through 
the  soil.  With  such  large  amounts,  there  is  no  need  of 
specially  placing  some  of  it  near  the  plants,  as  a  fraction 
is  enough  to  act  as  a  starter. 

At  the  present  time  heavy  applications  of  fertilizer  are 
used  in  the  specialized  potato-growing  districts  in  this 
country,  with  the  idea  of  supplying  so  much  that  the  grow- 
ing plant  will  never  suffer  for  lack  of  plant-food  at  any 
time.  For  such  amounts  as  1000  to  3000  pounds  to  the 
acre,  broadcasting  is  coming  into  use  in  whole  or  in  part. 
Ordinary  grain-drills  or  special  broadcast  fertilizer  sowers 
are  used.  All  fertilizers  broadcasted  should  be  thoroughly 
worked  into  the  soil.  While  there  is  some  tendency  for 
soluble  fertilizer  salts  to  work  downward  into  the  soil, 
there  is  likely  to  come  any  summer,  after  potatoes  are 
planted,  a  hot  and  dry  time  when  several  inches  of  the  top 
soil  is  very  dry.  The  fertilizer  in  such  a  dry  soil  is  prac- 
tically useless  to  the  crop  for  lack  of  sufficient  water  to  dis- 
solve it.  This  is  especially  true  when  a  surface  mulch  of 
dry  soil  is  maintained  for  the  purpose  of  conserving  the 
moisture  in  the  earth  below.  This  accounts  for  some  of  the 
contradictory  results  obtained  by  experimenters  on  com- 
parisons of  the  application  of  fertilizers  by  the  drill  and 
broadcast  methods.  Under  the  conditions  of  northern 
Maine,  in  which  the  water  in  the  soil  is  usually  abundant, 
part  of  the  heavy  fertilizer  used  is  often  put  on  after  the 
plants  are  up,  being  applied  to  the  ridge  and  covered  with 
soil.  It  is  doubtful  whether  this  method  would  be  a 
success  in  other  regions,  even  in  some  other  parts  of 


128  The  Potato 

Maine/  unless  soil  moisture  conditions  are  fairly  certain 
to  be  favorable  at  the  time  of  the  second  application. 
Nitrate  of  soda  may  be  applied  at  any  time,  as  it  is  so 
easily  dissolved.  Success  with  any  method  of  applying 
fertilizer  depends  on  soil  moisture  conditions.  The  correct 
method  in  one  case  may  be  entirely  wrong  in  another. 

The  writer  has  developed,  for  his  own  farm  conditions, 
a  method  which  has  been  very  successful  for  applying 
large  amounts  of  fertilizer.  The  soil  is  a  silt  loam  of  good 
water-holding  capacity,  further  increased  by  the  incorpora- 
tion of  large  quantities  of  organic  matter.  The  total  rain- 
fall for  the  whole  year  averages  under  30  inches.  Periods 
of  dry  weather  after  planting,  sometimes  extending  to 
several  weeks,  keep  the  surface  soil  very  dry.  In  some 
fertilizer  experiments,  acid  phosphate  applied  as  a  top- 
dressing  after  planting  did  not  become  dissolved  to  produce 
much  increase  in  yield.  At  the  same  time,  when  it  was 
applied  deeper  in  the  soil  before  planting,  a  good  increase 
resulted.  The  soil  is  deep,  and  potato  roots  easily  pene- 
trate to  the  depth  of  several  feet.  The  fertilizer  is  usually 
1500  to  2000  pounds  of  a  mixture  of  acid  phosphate  and 
muriate  of  potash. 

Part  of  the  fertilizer  is  sown  broadcast  in  early  spring 
on  the  surface  of  fall-plowed  land,  thoroughly  disked  in  to 
the  depth  of  7  to  8  inches  and  the  field  replowed  to  the 
depth  of  10  inches.  The  remainder  of  the  fertilizer  is  then 
applied  and  disked  in  as  before.  The  essential  idea  of  this 
method  is  to  have  a  large  amount  of  fertilizer  so  evenly 
and  thoroughly  distributed  through  the  soil  to  the  depth 
of  10  inches  that  the  potato  roots  are  drawn  out  and  down 
completely  to  fill  this  whole  space,  rather  than  to  have  a 
tendency  to  remain  in  the  more  limited  space  occupied 
1  Maine  Agri.  Expt.  Sta.  Bui.  246. 


Manures  and  Fertilizers  129 

by  the  fertilizer  when  either  the  drill  or  the  broadcast 
method  of  sowing  is  used.  Scientific  experiments  show 
that  roots  multiply  mostly  in  the  soil  where  the  supply 
of  plant-food  is  most  abundant.^  The  surface  mulch 
of  dry  soil  keeps  the  lower  parts  both  moist  and  cool. 
Later  the  heavy  tops  shade  the  ground  with  the  same 
result.  This  cool  lower  soil,  although  itself  too  dry  for 
roots  to  grow  in,  is  a  marked  advantage  in  hot  seasons  in 
preventing  degeneration  of  the  potato  as  well  as  in  increas- 
ing yield. 2 

This  method  of  applying  fertilizers  has  produced  very 
striking  results  in  dry  seasons.  In  periods  of  extreme 
drought  the  tops  showed  but  little  injury  from  tip-burn  and 
grew  continuously.  The  writer  thinks  that  this  success 
is  due  to  the  greater  moisture  supply  made  available  to 
the  plants  by  the  wide  and  deep  distribution  of  the  root 
system.  This  enables  the  plants  to  find  and  utilize  the 
water  in  a  larger  volume  of  soil  at  the  time  when  the 
plants  need  it  most.  When  the  roots  are  encouraged 
to  develop  near  the  surface  by  broadcasting  the  fertilizer 
and  working  it  in  shallowly,  the  drying  of  the  upper  soil 
layer  deprives  the  plants  of  the  use  of  much  of  their  root 
system,  and  may  leave  them  in  poorer  shape  to  with- 
stand hard  conditions  than  if  the  roots  had  been  forced  to 
spread  out  and  down  earlier  to  find  plant-food.^  In  the 
corn-belt,  dry  weather  in  June  is  recognized  as  a  favorable 
factor  for  the  future  success  of  the  corn  crop  because  it 
forces  the  plants  to  root  deeply,  while  a  wet  June  would 
result  in  shallow  rooting  which  would  be  certain  to  suffer 
later  in  the  summer. 


1  Storer,  "  Agriculture."      Vol.  1,  pp.  297-300. 

"  Neb.  Agr.  Expt.  Sta.  Bui.  146  ;   and  Colo.  Agr.  Expt.  Sta.  Bui.  216. 
'  Bureau  of  Soils.  Bui.  22,  p.  52. 
K 


130  The  Potato 


FARM  MANURES 


Farm  manures  increase  the  productiveness  of  the  soil 
in  four  ways  :  first,  by  the  actual  plant-food  added  to  the 
soil ;  second,  by  the  physical  effect  of  loosening  and 
aerating  the  soil  and  adding  to  its  moisture-holding  ca- 
pacity ;  third,  by  the  action  of  the  organic  matter  of  the 
manure  in  making  available  to  the  plants  by  its  decay  the 
insoluble  plant-food  of  the  soil ;  and  fourth,  by  improving 
the  soil  conditions  for  the  work  of  the  beneficial  bacteria. 
Any  computation  based  on  the  trade  value  of  the  plant- 
food  may  be  falsified  by  the  other  values  being  even  more 
important.  A  better  way  is  to  consider  the  results  ob- 
tained in  farm  practice  by  particular  crops  through  a 
series  of  years  long  enough  for  the  residual  effect  of  the 
manure  on  the  soil  to  be  measured.  The  potato  usually 
responds  well  to  the  use  of  manure  throughout  the  humid 
sections,  and  the  increase  in  yield  of  a  cash  crop  like  the 
potato  gives  quick  returns  for  the  use  of  the  manure. 

There  is  some  danger  that  common  scab  will  be  worse  on 
potatoes  grown  on  land  heavily  manured.  This  danger 
is  reduced  by  using  smaller  amounts,  by  having  the 
manure  rotted,  and  by  spreading  some  time  before  plant- 
ing. Horse  manure  is  thought  by  some  to  favor  scab 
more  than  other  manures,  but  this  is  doubtful. 

Manures  are  poorly  balanced  fertilizers.  They  contain 
relatively  much  more  of  nitrogen  than  of  the  other 
plant-food  elements  and  are  likely  to  produce  plants 
with  large  growth  of  tops  without  corresponding  tubers. 
This  can  be  prevented  by  using  with  the  manure  50 
pounds  of  acid  phosphate  to  each  ton,  and  in  rare 
cases  potash  may  be  added  also.  Coarse  and  strawy 
manure   may   make   some   soils   too    open   and  porous, 


Manures  and  Fertilizers  131 

causing  them  to  dry  out,  particularly  in  dry  years  and 
dry  climates. 

A  practice  in  handling  manure  that  is  gaining  ground  is  to 
apply  it  to  the  hay  crop  preceding  potatoes  in  the  rotation. 
By  increasing  the  yield  of  the  hay,  the  organic  matter  left 
in  the  soil  by  the  roots,  stubble  and  aftermath  is  increased 
for  the  use  of  the  potatoes  later.  When  manure  is  applied 
directly  to  the  potato  crop,  it  is  better  spread  in  the  pre- 
vious fall  or  winter  than  just  before  plowing.  The  manure- 
spreader  does  better  work  than  hand-spreading  because  of 
the  practical  impossibility  of  getting  as  even  distribution 
with  a  fork  as  wdth  the  machine.  Unless  the  potato- 
grower  has  only  a  small  area,  it  is  more  profitable  to  give 
the  whole  a  thin  coat  of  manure  than  to  have  parts  heavily 
covered  and  the  remainder  without  any.  Experiments 
extending  over  many  years  show  that  the  profit  to  a  ton 
decreases  as  the  size  of  .the  application  increases.  The 
manure-spreader  has  an  advantage  over  hand-spreading 
in  this  respect  because  smaller  amounts  to  the  acre  can  be 
spread  evenly. 

The  value  of  farm  manure  is  greatly  reduced  by  poor 
methods  of  handling.  The  best  net  returns  from  its  use 
come  from  spreading  as  soon  as  possible  after  it  is  made. 
When  necessary  to  keep  it  for  some  time,  as  when  fields 
are  occupied  by  growing  crops  in  summer,  precautions 
should  be  taken  to  prevent  loss.  Exposure  to  rains  may 
leach  away  half  the  value  in  a  short  time.  By  heating  in 
piles,  much  of  the  nitrogen  escapes.  Keeping  under  cover 
prevents  leaching.  Keeping  in  shallow^  piles,  tramping  by 
animals  and  occasional  wetting  prevents  heating.  Land 
plaster  and  other  substances  are  mixed  with  the  manure 
to  prevent  the  loss  of  nitrogen.  Raw  rock  phosphate 
or  "  floats  "  is  valuable  for  this  purpose  in  addition  to 


132  The  Potato 

its  phosphoric  acid,  the  element  needed  to  balance  the 
manure  as  a  potato  fertilizer.  Acid  phosphate  is  valu- 
able for  this  purpose,  but  it  must  not  be  used  under  the 
feet  of  animals.  Manure  spread  in  the  winter  suffers  no 
loss  from  heating  and  but  little  from  leaching  unless  the 
field  is  so  sloping  that  water  runs  off  rapidly.  It  is  so 
difficult  to  prevent  loss  in  manure  kept  in  other  ways 
that  spreading  as  rapidly  as  made  is  the  best  method  in 
most  cases. 


REFERENCE 

VoELCKER  and  Hall.     The  Valuation  of  Unexhausted  Manures. 


CHAPTER  VII 

PLANTING 
By  Daniel  Dean 

Soil  preparation  for  planting  potatoes  should  be  such 
as  will  meet  the  peculiar  demands  of  the  potato  plants. 
A  loose  and  mellow  soil  is  needed  for  extension  of  the  weak 
and  tender  roots  and  for  the  development  of  the  tubers. 
Preparation  should  be  designed  to  correct  the  faults 
of  the  local  soil  and  climate  as  far  as  that  can  be  accom- 
plished. Preparation  before  planting  should  be  such  as 
will  reduce  the  tillage  after  planting  as  much  as  possible. 
Weeds  are  more  cheaply  killed  by  wide-spreading  tools, 
like  harrows  and  disks,  than  by  small,  single-row  tools 
or  by  hand  hoeing  later. 

Fall  plowing  is  of  great  value  in  all  but  the  lighter 
soils.  It  rots  the  soil  organic  matter,  puts  the  land  into 
better  physical  condition  by  exposing  the  bare  soil  to 
winter  freezing,  stores  up  more  water  for  the  use  of  the 
crop  and  sprouts  and  kills  part  of  the  weed  seeds  in  the 
ground.  The  control  of  insects,  like  the  white  grub 
and  wire-worm,  is  easier  with  fall  plowing  because  the 
larvae  are  more  exposed  to  freezing  and  to  attacks  of 
their  natural  enemies,  such  as  birds.  As  a  rule,  the 
heavier  a  soil,  the  more  it  is  benefited  by  fall  plowing. 
There  is  some  saving  in  labor  by  fall  plowing  in  the 
northern  states  because  potatoes  are  usually  followed 
133 


134  The  Potato 

by  spring-sown  grain,  which  requires  considerable  work 
early  in  the  spring.  The  harrowing  needed  to  place 
fall-plowed  land  in  condition  for  planting  takes  less 
time  than  spring  plowing  and  the  harrowing  necessary 
to  cut  up  the  sod  well.  Harrowing  must  be  deep  and 
thorough  or  the  benefit  of  fall-plowing  may  be  largely 
lost.  While  there  is  some  additional  loss  of  moisture 
from  plowing  a  second  time  in  spring,  this  later  plowing 
greatly  reduces  the  amount  of  harrowing  necessary  and 
makes  certain  that  the  soil  is  well  pulverized  to  the 
depth  of  the  furrow.  It  is  well  to  fall-plow  land  as 
roughly  as  possible  wdth  the  furrows-slice  standing  nearly 
on  edge.  A  rough  surface  catches  the  rains  better,  ex- 
poses the  soil  better  to  the  action  of  frosts  and  reduces 
the  damage  by  winds  through  the  winter.  Water  is 
saved  in  fall-plowed  soil  because  the  layer  of  sod  or 
trash  at  the  bottom  of  the  furrow  prevents  the  water 
in  the  subsoil  from  escaping  as  readily.  Straw  or  manure 
spread  on  the  surface  before  fall  plowing  will  usually 
become  rotted  enough  by  spring  to  give  little  trouble  if 
replowed.  The  mellow  soil  with  rotting  organic  matter 
holds  more  water  than  unplowed  land  would,  especially 
in  places  like  dry  knolls.  Clover  sods  rot  quickly,  but 
sods  of  the  grasses  take  longer.  With  spring  plowing 
only,  it  is  beneficial  to  cut  up  the  grass  sods  with  a  disk 
harrow  before  plowing.  The  sod  rots  more  quickly  and 
the  soil  settles  together  better  so  that  the  movement  of 
the  water  in  the  soil  is  not  hindered. 

Earliness  is  a  great  advantage  in  spring  plowing  in  the 
northern  states.  An  experiment  by  King  at  Wisconsin 
showed  that  water  equal  to  If  inches  of  rainfall  was 
evaporated  in  one  week  in  spring.  Water  evaporates 
from  the  soil  very  fast  in  the  first  days  of  spring  after 


Planting  135 

the  frost  goes  out.  This  water  can  seldom  be  fully 
replaced  by  later  rains.  Its  conservation  may  often 
turn  the  scale  between  success  and  failure  in  droughts 
late  in  the  season.  Fall  plowing  has  here  an  advantage 
over  spring  plowing  because  it  is  possible  to  cover  many 
acres  with  harrow  or  disk  in  a  few  days  as  soon  as  the 
ground  can  be  worked  without  injury  in  the  spring. 
By  going  over  fall-plowed  potato  ground  once  before 
sowing  spring  grain,  the  saving  in  moisture  for  the  potato 
crop  will  more  than  pay  for  any  loss  of  grain  by  slightly 
delayed  sowing. 

TILLAGE   TOOLS 

The  plow  is  the  standard  implement  of  tillage.  Ex- 
cept in  special  cases,  nothing  has  been  found  to  equal 
its  work.  The  common  plows  used  in  the  East  and 
South  are  drawn  by  one,  two  or  three  horses  or  mules. 
The  two-bottom  reversible  sulky  plow  is  coming  much 
into  use  in  the  East.  It  is  heavier  and  more  expensive 
than  the  common  plow,  but  will  work  better  in  soils  of 
varying  hardness,  and  in  plowing  alfalfa  sod.  This 
reversible  sulky  plow,  like  the  ordinary  two-bottom  gang 
sulky  used  in  the  central  West,  does  poorer  work  in  plow- 
ing mider  straw,  stalks  and  the  like  than  the  ordinary 
walking  plow.  The  plow  can  turn  under  sods,  and  so 
forth,  more  perfectly  than  any  other  tool,  and  its  use 
distributes  surface  organic  matter.  The  jointer  enables 
sod  and  trash  to  be  buried  more  completely. 

The  type  of  harrow  to  be  used  depends  upon  the  work 
to  be  done.  Harrows  may  be  used  merely  to  fine  and 
smooth  a  rough  surface,  like  the  spike-tooth  harrow,  or 
may  be  designed  to  tear  up  and  fine  the  soil  to  consider- 
able depth,  like  the  disk  and  spring-tooth  types.     The 


136  The  Potato 

disk  and  its  variation,  the  cutaway,  are  used  most  in 
soils  nearly  or  quite  free  from  stone.  With  these  the 
soil  can  be  thoroughly  fined  nearly  to  the  depth  of  the 
plowed  furrow.  The  disk  will  cut  up  sods  or  straw  and 
will  work  in  soils  so  full  of  weed-roots  that  other  types 
of  harrows  will  be  clogged.  The  spring-tooth  harrow  is 
used  more  than  the  disk  in  sections  with  stony  soils.  It 
pays  to  keep  the  cutting  edges  of  the  disk  or  the  points 
of  the  teeth  sharp.  The  spike-tooth  smoothing  harrow 
should  follow  the  disk  to  level  the  surface  before  plant- 
ing. It  is  also  valuable  to  keep  a  surface  mulch  before 
planting  and  to  kill  weed  seeds  that  have  sprouted. 

The  roller  is  a  tool  of  great  value,  but  is  often  used 
with  poor  judgment  in  potato-growing,  because  it  has 
considerable  weight  for  the  small  surface.  Its  action, 
resting  on  the  soil,  is  to  firm  the  earth  to  a  considerable 
depth,  something  seldom  necessary  with  potatoes  unless 
on  very  light  soil,  and  is  often  harmful.  Used  to  follow 
the  plow  after  plowing  in  the  spring,  it  may  help  to  pre- 
vent sods  on  edge  from  making  open  spaces  in  the  soil. 
Too  often  it  is  used  with  the  idea  that  it  is  necessary, 
as  with  the  grains  and  grass  seeds,  to  firm  soil  around 
the  seeds  to  furnish  moisture  for  germination.  The 
roller  is  used  to  assist  the  germination  of  grain  and  grass 
by  packing  the  soil  around  them,  causing  it  to  become 
damp  by  the  capillary  rise  of  water.  Such  seeds  are 
dry  and  need  water  to  start,  and  their  small  size  demands 
closely  packed  soil  for  the  benefit  of  the  roots.  Unlike 
the  dry  grain  seeds,  the  large  potato  seed-pieces  have  all 
the  water  they  need,  80  per  cent,  and  can  grow  for  weeks 
without  any  from  the  soil.  This  fact  is  familiar  to  those 
who  have  seen  potatoes  in  cellars  send  shoots  to  the 
length  of  several  feet.     Soils  are  seldom  too  loose  for  the 


Planting  137 

potato  and  are  very  often  too  hard.  The  plank  float, 
or  clod  crusher,  is  a  better  tool  to  crush  lumps,  and  does 
not  settle  the  soil  below  the  surface  as  does  the  roller. 
Such  lumps  crush  easiest  a  few  hours  after  a  rain. 

The  depth  of  plowing  for  the  potato  should  be  as  great 
as  the  fertility  of  the  soil  will  permit.  The  weak  potato 
roots  need  all  the  space  they  can  get.  Outside  of  the 
arid  regions  of  the  United  States,  care  must  be  taken 
not  to  expose  much  of  the  cold  and  infertile  subsoil  at 
any  one  plowing.  Where  it  is  necessary  to  plow  land 
deeper  than  formerly,  not  over  one  inch  of  subsoil  should 
be  turned  up  at  a  time.  Organic  matter  must  be  added 
to  lighten  the  subsoil  turned  up,  as  it  is  very  deficient  in 
this.  Sandy  soils,  in  which  potato  roots  penetrate  easily, 
need  deep  plowing  less  than  heavy  soils.  Only  three  to 
five  inches  is  used  in  some  sandy  sections.  Heavier 
soils,  if  well  provided  with  humus,  are  frequently  plowed 
to  the  depth  of  ten  inches  or  more,  usually  about  6  or 
7  inches. 


RESULTS   OF  TILLAGE 

The  results  of  soil  tillage  are : 

(1)  The  organic  matter  in  stubble,  manure,  and  the 
like  is  buried  in  the  soil,  to  decay  there. 

(2)  The  mineral  particles  are  made  finer,  and  fresh 
surface  exposed  to  the  action  of  solvents,  such  as  soil 
water  and  carbonic  acid. 

(3)  The  soil  organic  matter  is  broken  up  and  easily 
changed  into  more  useful  forms.  The  rapidity  with 
which  soil  organic  matter  is  destroyed  by  tillage  is 
little  appreciated.  The  common  saying,  that  "tillage 
is  manure,"  is  practically  true.     Tillage  is  expensive  in 


138  The  Potato 

labor  and  also  expensive  in  the  changes  it  produces  in 
the  soil.  A  soil  thoroughly  tilled  for  a  potato  crop  has 
thereby  lost  a  considerable  amount  of  organic  matter. 
The  expense  of  replacing  this  must  be  considered  in  the 
final  profit-and-loss  account  of  the  crop.  In  many  parts 
of  the  United  States,  potato-growing  has  gained  a  bad 
reputation  from  the  rapidity  with  which  it  reduces  the 
fertility  of  the  soil.  In  others,  where  organic  matter  is 
kept  up  by  good  rotation  and  where  fertilizers  are  used 
heavily,  potato-growing  is  regarded  as  a  sure  way  to 
enrich  the  land,  A  single  tilled  crop,  like  potatoes  or 
corn,  places  the  soil  in  better  physical  condition  to  grow 
succeeding  crops  of  grain  and  hay.  The  alternation  of 
tillage  crops,  which  excite  and  increase  bacterial  activity, 
with  the  hay  crop  will  provide  organic  matter  as  a  food  for 
the  bacteria  and  thereby  keep  up  fertility  at  low  expense. 

(4)  The  increase  of  the  volume  of  the  air-spaces  of  the 
soil  by  thorough  tillage  greatly  increases  the  chemical 
and  bacterial  activities  of  the  soil.  The  oxygen  of  the 
air  combined  with  the  organic  matter  of  the  soil  causes 
the  formation  of  carbon  dioxide.  This,  in  turn,  acts 
with  the  soil  water  as  a  solvent  of  mineral  compounds, 
such  as  insoluble  phosphoric  acid.  The  beneficial  bac- 
teria of  the  soil  are  favored  by  plenty  of  air  in  the  soil 
and  increased  greatly  in  number  and  activity.  Their 
action  increases  the  availability  of  the  soil  plant-food. 
Some  species  of  soil  bacteria  are  injurious.  As  these 
mainly  thrive  where  little  or  no  air  is  present,  tillage  re- 
duces their  effect. 

(5)  Tillage  exposes  fresh  soil  surfaces  to  the  air  and  at 
first  causes  some  loss  of  moisture.  Loosening  the  surface 
soil  by  tillage  prevents  evaporation  from  the  lower  parts 
of  the  soil  by  breaking  up  capillary  connection  between 


Planting  139 

the  soil  under  the  tilled  area  and  the  surface.  Until 
capillary  action  is  again  established  by  the  settling  to- 
gether of  the  tilled  soil,  but  little  water  can  be  lost  by 
evaporation.  A  thin  layer  only  of  loose  soil  is  sufficient 
to  prevent  evaporation.  A  thin  layer  settles  together 
sooner  than  a  thick  one  and  needs  breaking  more  often. 
More  emphasis  has  usually  been  placed  on  tillage  of 
potatoes  after  planting  than  before  planting.  The 
great  soil  supply  of  water  in  late  winter  and  early 
spring  presents  opportunities  for  conservation  that  exceed 
those  during  the  growing  period  of  the  crop.  In  recent 
years  a  change  has  come  about  in  the  attitude  of  inves- 
tigators towards  the  value  of  summer  tillage.  Extended 
experiments  have  shown  that  one  factor  which  was 
largely  neglected  by  early  experimenters  is  of  impor- 
tance —  this  is  the  ability  of  the  plant  root  to  seize 
upon  the  use  of  soil  moisture.  When  the  soil  is  not 
occupied  by  a  growing  crop,  there  is  no  doubt  that  a  sur- 
face mulch  of  loose  soil  does  conserve  moisture  by  pre- 
venting evaporation,  but  when  the  soil  is  well  filled  with 
plant  roots,  there  is  little  more  water  evaporation  from 
untilled  soil  than  from  tilled.  The  gains  in  yields  ob- 
served from  tillage  come  from  another  source  —  weed 
killing  —  rather  than  from  prevention  of  the  evapora- 
tion. This  means  that  the  farmer  will  till  practically 
as  much  as  under  the  former  practice,  but  will  have  in 
mind  weed  killing  as  his  principal  object,  instead  of  pre- 
venting loss  of  water.  In  practice  this  will  mean  that  the 
tillage  of  the  potato  crop  during  the  growth  of  the  crop 
will  be  done  earlier  than  has  been  the  custom.  Water 
will  be  conserved  by  fall  plowing  where  possible ;  by  the 
addition  of  organic  matter  to  the  soil ;  and  by  early  spring 
tillage  to  save  the  water  supply.     The  soil  will  not  be 


140  Tfie  Potato 

allowed  to  dry  out  for  the  late  main  crop  of  the  northern 
states  before  planting.  All  this  early  tillage  also  kills 
many  weeds  which  have  formerly  been  left  to  be  killed 
by  inter-tillage  later  on. 

After  planting  there  is  a  period  of  several  weeks  when 
large  and  wide  tools  can  be  used  to  advantage  in  tillage. 
The  harrow,  leveler  and  weeder  cover  several  planted 
rows  at  once  and  kill  weeds  very  cheaply,  besides  saving 
moisture. 

The  necessity  of  weed  killing  for  the  production  of 
large  crops  is  even  greater  than  the  saving  of  moisture 
by  tillage.  Weeds  not  only  rob  the  potatoes  of  mois- 
ture, but  are  able  by  their  stronger  root  systems  and 
greater  foraging  ability  to  seize  upon  and  use  the  soluble 
plant-food  in  the  soil.  Very  small  weeds  in  this  way 
injure  the  potato  crop  more  than  would  be  supposed. 
The  weeds  which  sprout  from  seeds  in  the  soil  are  more 
easily  killed  before  coming  up  than  afterward.  The 
tender  shoots  from  the  seeds  are  killed  by  a  light  stirring 
of  the  soil  which  would  not  affect  them  at  all  a  few  days 
later.  The  sprouts  starting  from  the  seed  have  but  little 
vitality  until  they  can  reach  the  surface,  and  produce 
green  leaves.  Then  roots  start  to  secure  plant-food  which 
is  worked  by  the  leaves  into  material  for  further  growth. 
Every  day  now  adds  to  the  ability  of  the  young  weed  to 
stand  punishment  and  live.  Several  successive  crops  of 
weed  seeds  can  be  sprouted  and  killed  by  tillage  between 
planting  and  the  time  when  the  potato  tops  are  six  inches 
high.  Tillage  at  this  time  can  be  done  carefully  enough 
to  prevent  injury  to  the  growing  sprout  of  the  potato 
before  it  comes  up  and  until  it  is  established  for  itself 
in  the  soil.  Perennial  weeds  with  root  stalks,  like  quack 
or  witch-grass,  are  much  easier  controlled  by  previous 


Planting  141 

cultivation  in  the  fall  or  early  spring  than  by  tillage  during 
the  life  of  the  potato.  The  reserve  of  nourishment  in  the 
root  stalks  enables  them  to  stand  punishment  for  several 
weeks  and  recover  from  it  to  injure  the  potato  after 
tillage  is  no  longer  possible. 

The  preceding  results  of  tillage  have  all  been  favorable 
to  the  potato  plant.  Tillage  has  another  action  which 
has  not  been  sufficiently  studied  and  which  has  led  to 
many  conflicting  results  in  experiments  and  in  farmers' 
practice.  It  is  a  fact  that  tillage  can  injure  the  potato 
plant  even  easier  than  it  can  the  tough  and  hardy  weeds. 
It  is  very  difficult  to  work  with  soil  near  the  potatoes 
without  injuring  them.  As  the  season  advances,  this 
becomes  more  dangerous  to  the  potato.  While  the 
young  plant  is  still  attached  to  the  seed  piece  and  draw- 
ing on  it  for  nourishment,  it  can  lose  part  of  its  small 
roots  without  great  loss,  particularly  as  the  weather  is 
yet  cool  and  favorable  to  the  vitality  of  the  crop.  Each 
day  the  potato  grows  older  increases  the  danger  of  loss  of 
yield  from  injurious  root  injury.  In  the  later  part  of 
the  plant's  life,  the  whole  upper  soil  becomes  filled  with 
roots.  These  come  so  close  to  the  surface  that  it  is  most 
difficult  to  work  any  tillage  tool  without  some  injury. 
Few  tools  except  the  hand  hoe  can  be  worked  as  shallow 
as  one  inch,  and  many  of  the  larger  roots  are  that  close 
to  the  surface.  Under  some  conditions,  late  tillage  may 
do  less  injury  to  the  potatoes  than  under  others.  In 
periods  of  abundant  rainfall,  the  plants  may  tend  to 
root  too  close  to  the  surface  and  some  root-pruning  may 
force  the  potato  to  root  deeper.  If  drought  comes  later, 
this  will  be  a  benefit  to  the  crop.  In  very  cool  seasons 
in  which  the  potato  does  not  suffer  from  extreme  heat, 
root-pruning  by  tillage  tools  does  less  damage  than  in 


142  The  Potato 

hot  and  dry  seasons.  The  loss  in  yield  from  tillage  at 
the  wrong  time,  too  deep,  or  too  close  to  the  plants, 
often  amounts  to  a  large  percentage  of  the  crop.  The 
greatest  danger  from  excessive  tillage  is  likely  to  come 
in  the  northern  states  in  which  late  cultivation  of  the 
main  crop  comes  at  the  hottest  time  of  summer.  When 
the  "critical  period"  of  the  plant's  life  comes  at  the 
time  when  climatic  conditions  are  most  unfavorable  to 
the  potato,  any  injury  to  the  roots  is  likely  greatly  to 
reduce  the  yield. 

PLANTING 

The  time  of  planting  depends  on  the  market  for  which 
the  crop  is  grown  and  the  local  soil  and  climate.  The 
higher  prices  received  for  extreme  earliness  in  the  south- 
ern truck  crop  compel  the  use  of  short-season  varieties, 
like  the  Triumph  and  Cobbler,  and  planting  very  early 
to  get  the  crop  on  the  market  before  prices  fall.  All 
cultural  methods  are  arranged  with  this  end  in  view,  so 
there  is  little  choice  in  the  time  of  planting.  Along  the 
Canadian  border  and  in  much  of  the  Rocky  Mountain 
section  the  whole  growing  season  is  but  little  longer  than 
the  life  of  main-crop  varieties.  But  in  most  of  the  prin- 
cipal growing  states,  from  New  England  to  Iowa  and 
Nebraska,  it  is  possible  to  vary  the  time  of  planting 
by  several  weeks.  Here,  as  a  rule,  most  potatoes  are 
now  planted  in  late  May  and  in  June.  The  later  plant- 
ings yield  better  because  the  crop  matures  in  cooler 
weather  than  with  early  planting.  Moisture  is  more 
likely  to  be  abundant  in  fall  than  in  late  summer.  The 
dangers  of  late  planting  are  late-blight  and  rot,  —  unless 
spraying  with  bordeaux  is  practiced,  —  injury  from  early 
frost  and  early  fall  freezing  of  the  soil,  and  conflict  of 


Planting  143 

the  later  tillage  of  the  crop  with  the  rush  period  of 
haying  and  harvesting.  But  increasing  competition  of 
the  southern  crop  is  forcing  many  growers  to  abandon  the 
previously  profitable  early  crop  for  local  trade.  Bordeaux 
spraying  has  been  found  to  lengthen  the  life  of  the  potato, 
and  potatoes  to  be  sprayed  may  be  planted  slightly  earlier 
than  those  unsprayed,  for  that  reason. 

The  methods  of  ridging  and  level  culture  with  deep 
and  shallow  planting  are  best  illustrated  by  their  use  in 
two  of  the  best-known  potato-growing  regions  of  the 
United  States.  Ridge  culture  with  comparative  shallow 
planting  is  used  in  Maine.  The  northern  latitude  of 
Maine  makes  the  growing  season  short  compared  with 
the  southern  states.  The  mean  temperature  of  the 
month  of  July  is  only  62°  to  65°  F.  Frosts  are  frequent 
in  June  and  September  and  may  occur  in  August.  Not 
much  field  work  can  be  done  before  the  month  of  May, 
and  October  10th  is  regarded  as  the  danger  line  beyond 
which  potatoes  are  likely  to  be  frozen  in  the  ground. 
Only  a  short  distance  away  in  the  Atlantic  Ocean,  the 
cold  ocean  current  from  the  Arctic  reaches  the  warm  Gulf 
Stream.  The  fogs  of  the  fishing  banks  here  are  well 
knowm.  The  rainfall  is  heavy  and  is  seldom  deficient 
throughout  the  growing  season.  The  rainfall  of  winter 
is  largely  available  to  the  potato  crop.  The  ground  is 
covered  with  snow  all  winter  and  the  loss  by  run-off  and 
evaporation  before  time  of  planting  is  much  less  than 
that  of  the  other  great  producing  states.  The  soil  con- 
ditions of  Aroostook  County,  the  great  potato-producing 
section  of  Maine,  are  favorable  for  the  retention  of  soil 
water.  Most  of  that  section  has  been  cleared  from  the 
forests  only  a  few  years,  compared  with  the  longer  settled 
communities,  and  the  soil  is  well  supplied  with  organic 


144  The  Potato 

matter.  The  region  is  so  damp  that  the  higher  and 
dryer  parts  are  usually  considered  safer  and  better  for 
potatoes  than  those  lying  lower.  The  more  or  less 
gravelly  limestone  loam  soil  crumbles  Easily  and  seldom 
gives  trouble  by  baking.  With  such  conditions  under 
which  surplus  of  water  is  more  to  be  feared  than  a  de- 
ficiency, Maine  growers  use  an  extreme  ridge  culture. 
Instead  of  leveling  down  the  ridges  left  by  the  planter  and 
depending  mainly  on  the  use  of  leveling  tools  and  the 
weeder  to  kill  the  weeds  sprouting  among  the  plants  in 
the  row,  Maine  growers  kill  the  weeds  in  the  row  by 
ridging  several  times.  There  is  little  danger  that  the 
growing  plants  in  the  ridges  will  suffer  from  lack  of 
moisture.  Ridge  culture  is  also  the  favorite  in  the  ad- 
joining provinces  of  Canada,  in  which  conditions  are 
similar.  This  culture  is  suited  to  wet  climates  and 
wet  seasons.  Digging  is  rendered  easier  by  ridging 
where  the  soil  is  likely  to  be  wet.  The  first  ridging  after 
the  plants  come  through  the  ground  covers  the  small 
plants  and  prevents  injury  from*late  frosts.  In  many 
other  sections,  such  covering  would  result  in  baking 
the  soil.  Ridging  is  necessary  under  the  methods  of 
irrigation  in  order  to  prevent  injury  to  the  potato  plants 
from  the  irrigating  water. 

Long  Island  potato-growing  stands  as  an  example  of 
prosperous  farming,  where  a  different  method  than  the 
ordinary  is  used.  The  soil  of  Long  Island  is  a  rather 
light  sand  which  is  easily  tilled  and  dries  out  quickly 
after  rain.  Level  culture  is  used  because  much  better 
yields  are  secured  than  by  ridging.  Less  soil  surface  is 
exposed  to  evaporate  water  by  level  culture. 

Partly  owing  to  the  high  prices  in  late  summer,  Long 
Island  potatoes  are  planted  as  early  in  the  spring  as  the 


Planting  145 

ground  can  be  worked  —  last  of  March  and  April  — 
and  mature  in  the  dry  weather  in  July  and  August. 
Deep  planting  and  level  culture  exposes  less  of  the  easily 
heated  sandy  soil  to  the  sun  and  reduces  danger  of  heat 
injury  as  well  as  that  from  drouth.  The  light  soil  usually 
is  dry  at  digging  time,  gives  little  trouble  in  digging, 
though  sometimes  fields  left  late  before  digging  are 
ridged  to  kill  weeds  which  have  started.  Level  culture 
is  a  relative  term  as  some  earth  is  thrown  toward  the 
plants  by  the  teeth  of  the  cultivators.  This  prevents 
the  growing  tubers  from  being  sunburned.  Deep  plant- 
ing allows  the  soil  over  the  rows  to  be  thoroughly  worked 
in  the  week  subsequent  to  planting.  Weeds  are  easily 
killed  at  this  time  and  soil  water  conserved  for  the  later 
use  of  the  crop.  As  a  rule,  early  planted  potatoes  should 
be  put  in  shallower  than  late  potatoes,  as  the  sprouts 
start  more  slowly  in  the  cooler  soil.  Very  shallow  plant- 
ing is  seldom  advisable  unless  the  soil  is  so  wet  and  cold 
that  heavy  ridging  is  necessary  for  drainage.  Growers 
in  other  sections  of  the  country  use  methods  between 
the  two  extremes,  according  to  their  conditions.  The 
truck  crop  of  the  South  is  raised  under  soil  conditions 
similar  to  those  of  Long  Isfend.  The  need  of  securing 
warmth  in  the  soil  to  hasten  growth  leads  to  some  ridg- 
ing. Shallow  soils  with  hard-pan  close  to  the  surface 
as  in  the  volusia  soils  of  New  York,  Pennsylvania  and 
Ohio,  present  a  hard  problem.  Ridging  is  the  usual 
method  used  in  this  section  on  account  of  trouble  in  digging 
in  wet  seasons,  and  with  the  usually  stony  soil,  it  is  diffi- 
cult to  control  weeds  near  the  plants  by  the  use  of  other 
tools  than  those  which  ridge  the  rows.  Light  and  dry 
soils  particularly,  if  likely  to  be  fairly  dry  at  digging 
time,  do  better  with  nearly  level  culture. 


146  The  Potato 

The  advantages  of  having  sufficient  soil  over  the  seed 
to  permit  wide  tillage  after  planting  are  so  great  that  it 
pays  growers  to  plant  deep  enough  for  this  purpose. 
The  bottom  of  the  furrow  made  by  the  planter  or  marking 
tool  should  be  at  least  two  inches  below  the  level  of  the 
surface  of  the  soil  and  better  three  or  four;  for  sandy 
soil  likely  to  be  dry,  even  more.  Growers  are  often 
deceived  at  the  depth  they  plant  by  looking  at  the  depth 
of  the  mark  below  the  level  of  the  earth  thrown  out  by 
the  marking  tool  instead  of  taking  the  measure  from  the 
true  level  of  the  surface  soil  to  the  bottom  of  the  furrow. 

Hill  and  drill  'planting 

Two  principal  methods  of  planting  are  used  in  the 
United  States.  Potatoes  are  said  to  be  in  hills,  checks 
or  squares  when  the  ground  is  marked  both  ways  and 
the  seed  dropped  at  the  intersection  of  the  mark.  This 
method  is  much  used  for  hand  planting.  It  has  the 
advantages  of  permitting  cultivation  both  ways  and 
so  weeds  are  easier  kept  under  control.  With  poor  soils 
the  large  area  allowed  to  each  hill  is  an  advantage,  as 
each  hill  has  enough  space  to  produce  a  good  yield.  Rows 
in  the  United  States  are  from  30  to  42  inches  apart  ac- 
cording to  the  value  of  the  land,  the  amount  of  stone  in 
the  soil  and  according  to  the  fertility.  Unless  the  ground 
is  very  poor,  it  is  advisable  to  have  the  hills  closer  to- 
gether in  the  short  way  of  the  field  to  give  a  large  yield. 
Whew  planted  in  drills,  the  seed  is  planted  from  less  than 
12  inches  apart  in  the  row  in  the  best  soils,  to  sometimes 
nearly  2  feet  in  poor  soils.  Planting  in  drills  is  rapidly 
gaining  ground  in  the  United  States,  as  the  yield  from 
the  larger  number  of  hills  is  larger  to  the  acre  than  when 


Planting  147 

planted  in  hills.  Growers  in  all  the  important  potato- 
growing  sections  find  it  practicable,  by  modern  tillage 
methods,  to  keep  weeds  subdued  in  drills  as  well  as  in 
hills.  The  prices  received  for  potatoes  from  sections  in 
which  drill  culture  is  general  are  higher  than  from  those 
where  hill  culture  is  mainly  used.  City  markets  demand 
medium-sized  tubers,  and  pay  better  prices  than  for  the 
coarse  and  overgrown  tubers  raised  in  hills.  When 
machine  diggers  are  used,  digging  costs  the  same  when 
either  method  of  planting  is  employed.  With  hand 
digging,  the  larger  number  of  hills  to  the  acre  under  drill 
culture  takes  more  time  to  dig  than  with  hills  and  may 
reduce  the  acreage  by  limiting  the  amount  which  can  be 
dug  before  freezing  weather.  The  constant  improvement 
in  the  manufacture  of  diggers  is  producing  machines  that 
will  dig  in  very  stony  soils. 

The  general  rule  for  spacing  hills  is  to  vary  the  number 
of  hills  to  the  acre  according  to  the  yield  which  may  be 
expected.  As  the  distance  apart  decreases,  the  weight  of 
the  individual  hills  and  the  size  of  the  tubers  is  reduced 
and  the  total  yield  to  the  acre  is  increased.  The  cost  of 
planting  and  digging  may  be  increased.  Digging  close- 
planted  hills  is  rather  expensive.  The  smaller  size  from 
close  planting  brings  higher  prices  in  city  markets.  An  ex- 
treme case  of  close  planting  is  that  in  the  island  of  Jersey 
where  potatoes  are  planted  12  by  16  inches,  or  over 
32,000  hills  to  the  acre.  With  very  rich  soil  and  hand 
tillage,  a  yield  averaging  over  400  bushels  to  the  acre  is 
secured,  even  when  dug  for  the  early  market,  while  still 
growing.  The  ty^Q  of  the  potato  variety  affects  the 
spacing.  The  common  Rural  or  Blue  Sprout  type  sets 
fewer  tubers  to  the  hill  than  the  Green  Mountain  or 
White  Sprout  type  and  should  be  planted  closer  on  that 


148  The  Potato 

account  to  prevent  coarseness,  a  common  fault  complained 
of  by  city  buyers  in  Rurals.  Early  types  like  the  Bliss 
Triumph  and  Irish  Cobbler  are  usually  planted  closer 
together  than  late  varieties.  In  Europe  it  is  a  common 
practice  to  use  small  tubers  uncut  for  seed.  These  are 
often  secured  by  planting  very  close,  sometimes  as  little 
as  six  inches  apart  in  the  row.  As  before  noted,  wide 
spacing  allows  faster  digging  on  stony  soils.  Regions 
of  intensive  potato-culture,  such  as  Maine,  Long  Island 
and  the  coast-trucking  region,  usually  plant  rows  30  to 
36  inches  apart  and  the  seed  dropped  12  to  16  inches 
apart  in  the  rows  or  12,000  to  16,000  hills  to  the  acre. 
Regions  with  stony  soils,  as  the  Steuben  County  and 
Chateaugay  sections  of  New  York,  plant  to  some  extent 
in  checked  hills  about  3  feet  each  way  or  less  than  5000  hills 
to  the  acre.  The  regions  where  the  expense  for  rent  of 
land,  fertilizer  and  care  are  high  use  close  planting,  while 
low-priced  land  with  other  small  expenses  allows  more 
space  to  each  hill,  which  may  be  of  value  in  bad  seasons. 

Planting  tools 

Machine  planters  of  several  types  are  in  use  and  a 
larger  proportion  of  the  total  crop  is  planted  by  machinery 
each  year.  Hand  planting  is  used  mainly  in  stony  and 
rough  sections,  in  the  South  where  the  labor  is  cheap  and 
not  well  adapted  to  using  machinery  and  to  sections 
and  farms  where  potato-growing  is  of  small  extent  and 
regarded  as  secondary  to  otlier  farm  crops.  INIachine 
planters  are  nearly  universal  in  such  regions  of  intensive 
potato  culture  as  northern  Maine  and  Long  Island. 

IMachine  planters  are  of  two  types.  In  one  the  seed 
is  picked  up  from  a  hopper  and  dropped  by  revolving 


Planting  149 

pickers ;  in  the  other  the  seed  potatoes  are  fed  on  a  plat- 
form containing  a  revolving  wheel.  An  assistant  to  the 
driver  sits  behind  this  and  corrects  the  mistakes  of  the 
planter  by  removing  the  extra  pieces  where  two  or  more 
are  fed  between  pairs  of  spokes  and  by  filling  the  spaces 
which  are  empty.  The  first  requires  only  a  driver,  an 
advantage  where  labor  is  scarce.  The  picker  type  does 
fair  work  Avhere  the  seed  planted  is  small  and  round, 
and  on  smooth  land.  Its  efficiency  falls  off  with  the  use 
of  cut  seed  and  on  rough  or  stony  land.  The  picker  may 
injure  the  seed  and  spread  disease.  Picker  planters  are 
most  used  where  land  is  cheap  and  labor  high,  where 
cheap  cull  seed  is  used  wdth  mellow  soil  and  in  general 
where  it  is  the  object  to  raise  large  areas  at  low  expense. 
The  platform  type  planter  is  adapted  to  higher  priced 
land  where  every  missed  hill  is  expensive.  It  will  feed 
cut  seed  perfectly  with  much  less  trouble  to  the  feeder 
if  care  is  taken  to  cut  the  pieces  somewhat  blocky  in 
shape.  With  expensive  seed  and  wfien  spraying,  manure 
and  fertilizer  add  to  the  acre  cost,  it  does  not  pay  to 
have  any  missed  hills  to  cut  down  the  income  from  each 
acre.  The  cost  of  each  acre  is  the  same  whether  every 
hill  is  planted  or  not  and  the  cost  of  the  wages  of  the 
second  man  on  the  planter  is  small  compared  with  the 
increased  income. 

The  use  of  machine  planters  has  called  attention  to 
several  advantages  in  their  use  which  may  be  copied 
with  profit  by  growers  planting  by  hand.  The  saving  in 
cost  of  labor  over  hand  planting  may  or  may  not  be  great 
when  the  cost  of  the  machine  is  considered.  The  gain 
from  the  use  of  machine  planters  is  largely  in  other  ways. 
The  machine  opens  the  soil  with  a  small  plow  or  disk 
and  the  seed  is  dropped  into  soil  which  is  cool  and  damp. 


150  The  Potato 

There  is  no  tendency,  as  is  often  the  case  with  hand 
planting,  for  the  seed  to  become  dried  out  before  cover- 
ing. In  some  sections  as  on  Long  Island  there  is  trouble 
with  seed  slightly  infected  with  late-blight  germs  rotting 
in  the  ground  after  planting.  Trouble  of  this  kind  is 
much  worse  where  furrows  are  left  open  and  the  soil 
warmed  to  a  temperature  at  which  the  blight  germs 
develop  and  rot  the  seed.  Seed  which  becomes  dried  out 
before  or  after  planting  seldom  produces  as  good  a  yield 
as  where  it  is  allowed  to  keep  all  its  moisture.  The  seed 
planted  with  the  machine  planter  is  put  in  to  a  more  uni- 
form depth  than  seed  in  rows  dropped  by  hand  which  falls 
on  each  side  of  the  center  of  the  row  and  forces  the  culti- 
vator teeth  to  be  kept  away  on  account  of  injury  to  the 
plants  which  are  set  out  of  line  by  hand  planting.  The 
seed  dropped  by  a  machine  falls  in  a  straight  row  which 
is  less  liable  to  injury  from  cultivating  tools  than  that 
dropped  by  hand.  The  weeds  growing  next  to  the  plants 
are  the  ones  hardest  to  kill,  and  a  perfectly  straight  row 
easily  kept  clean  reduces  the  damage  from  weeds.  It  is 
uoticed  that  in  sections  where  machine  planters  are  in 
common  use  the  rows  are  usually  planted  close.  The 
soil  in  the  space  between  the  rows  is  so  tramped  by  horses 
and  wheels  of  tools  that  it  is  of  less  value  to  the  crop 
than  that  in  the  row.  The  yield  is  increased  by  a  larger 
number  of  rows  to  the  acre.  Planters  are  often  furnished 
with  a  fertilizer  attachment  which  applies  the  fertilizer 
along  with  the  seed.  The  fertilizer  should  be  dropped 
in  a  strip  several  inches  wide  and  covered  with  soil  before 
the  seed  is  dropped  or  the  sprouts  may  be  injured  by 
the  action  of  the  dissolved  fertilizer  salts. 


Planting  151 

Hand  planting 

More  potatoes  are  planted  by  hand  than  by  machines. 
If  well  done,  hand  planting  can  be  made  nearly  as  good 
as  machine  planting  in  some  respects  and  far  better  in 
others.  It  is  scarcely  possible  to  make  a  row  as  straight 
and  in  as  perfect  a  line  as  with  a  machine,  and  in  prac- 
tice the  seed  and  soil  must  be  exposed  to  drying  for  a 
short  time  at  least.  The  objection  is  often  made  that 
machines  cannot  be  made  to  plant  deep  enough.  Much 
hand  planting  is  too  shallow  because  the  tools  used  in 
marking  the  rows  do  not  make  the  marks  deep  enough. 
The  three  or  four  point  markers  used  in  many  sections 
cover  ground  fast,  but  the  marks  are  very  small.  In 
light  soils  these  markers  can  be  shod  with  iron  points 
large  enough  to  make  a  fair  mark.  In  heavier  or  stony 
soils  a  small  landside  plow,  or  better  a  wing  shovel  plow 
such  as  is  often  used  for  ridging  should  follow  the  marker 
to  deepen  the  furrows.  All  marking  tools  should  be  run 
with  great  care  to  keep  the  rows  straight.  Crooked 
rows  result  in  damage  to  the  potato  plants  by  the  culti- 
vator teeth  later  in  the  season.  Opening  the  furrows 
just  ahead  of  dropping,  and  covering  right  after,  reduces 
the  danger  of  drying  out  seed  and  of  warming  the  soil 
too  much.  Covering  the  seed  may  be  done  with  the  hoe 
or  with  a  small  plow,  with  a  shovel  plow  or  "middle 
buster"  in  the  South  or  with  a  hiller  with  wings  on  each 
side  of  the  row.  With  shallow  soils  the  hand  hoe  does 
the  poorest  work,  as  there  is  not  enough  earth  placed 
over  the  seed  to  allow  tillage  with  harrow,  weeder  and 
the  like.  Seed  covered  with  the  hoe  in  deep  soils  allows 
such  tillage  to  gradually  fill  up  the  mark,  at  the  same 
time  killing  many  weeds.     It  has  a  great  advantage  for 


152  The  Potato 

early  potatoes  in  heavy  soil,  as  the  amount  of  earth  covered 
over  the  seed  is  so  small  that  the  plants  come  up  much 
quicker  in  cold  springs  than  where  several  inches  of  dirt 
are  ridged  over  the  seed. 

SEED  POTATOES 

The  problem  of  conserving  the  full  vitality  of  the  seed 
potato  until  planted  is  a  hard  one  unless  cold  storage  is 
available.  The  white  sprouts  formed  in  ordinary  storage 
cellars  rapidly  reduce  the  vitality  of  the  seed,  are  easily 
broken  off  and  cannot  be  planted.  The  potato  requires  a 
resting  stage  for  some  time  after  maturity,  after  which  it 
starts  the  sprouts  rapidly  at  temperatures  as  low  as  50°  F. 
If  the  temperature  of  the  storage  space  can  be  kept  down 
to  from  34°  to  36°,  the  sprouts  will  not  start  and  the  whole 
strength  of  the  seed  will  be  saved  to  grow  the  crop.  Every 
attention  should  be  given  in  early  fall,  winter  and  spring 
to  keep  the  temperature  down.  Keeping  the  doors  and 
windows  open  on  cool  nights  and  closed  daytimes  in 
fall  and  spring  and  using  ice  to  keep  down  the  heat  re- 
duces the  sprouting.  Potatoes  intended  for  seed  in 
cellars  sprout  less  in  shallow  piles  on  the  floor  than  when 
piled  up  too  near  the  ceiling,  owing  to  difference  in  tem- 
perature. A  special  cold-storage  plant  would  be  ideal 
but  is  too  expensive  for  farmers  unless  for  very  large 
growers.  A  very  good  method  of  storing  seed  which  is 
falling  into  disuse  is  that  of  storing  in  pits  covered  with 
alternate  layers  of  straw  and  earth  to  prevent  freezing. 

A  European  practice  which  may  in  time  be  adopted  in 
America  is  that  of  greening  seed.  The  high  cost  of  land 
in  Europe,  low  cost  of  labor,  large  proportion  of  small 
tubers  in  the  varieties  grown,  vigor  of  small  tubers  which 


Planting  153 

makes  them  safe  for  use  as  seed,  use  of  immature  seed, 
and  trouble  with  seed  germinating,  have  led  to  the  use 
of  a  method  of  care  of  seed  by  which  it  is  kept  in  winter 
and  spring  in  shallow  trays  racked  up  in  buildings  so 
constructed  that  each  tuber  is  in  the  light.  The  sprouts 
at  the  seed  ends  start  and  grow  short,  green  and  stubby. 
When  planted,  these  potatoes  start  quickly  and  grow 
rapidly.  The  cost  of  the  equipment  and  of  the  labor 
required  to  place  the  seed  in  the  racks  and  again  to  place 
the  seed  in  the  ground  with  every  seed  end  up,  would  be 
very  heavy  in  America.  Unless  seed  which  has  been 
sprouted  in  this  way  for  some  time  is  planted  with  the 
sprouts  up,  there  is  trouble  in  loss  of  stand.  A  modifica- 
tion of  this  plan  may  be  used,  however,  for  American 
conditions  of  cost  of  labor.  Such  short  green  sprouts 
grown  in  the  light  for  a  short  time,  perhaps  two  weeks 
or  less,  will  not  be  broken  off  in  a  potato  planter  and  will 
give  no  trouble  about  coming  up.  It  is,  therefore,  prac- 
tical to  keep  the  seed  on  a  barn  floor  in  the  sun  for  that 
time  and  save  the  strength  of  the  sprouts  which  would 
be  lost  by  growth  in  a  cellar.  For  a  few  days  the  seed 
may  be  left  in  crates  in  the  sun  without  making  too  long 
sprouts  in  the  crates. 

Wlien  seed  potatoes  are  disinfected  with  formaldehyde 
solution  for  common  scab  or  with  corrosive  sublimate 
solution  for  both  rhizoctonia  and  scab,  the  crates  may  be 
disinfected  at  the  same  time  by  having  a  vat  of  solution 
in  which  the  crates  of  seed  are  immersed.  Soaking  too 
long  or  in  too  strong  solution  injures  the  vitality  of  the 
eye.  The  seed  must  not  be  cut  before  soaking  and  must 
be  dried  at  once  or  rot  may  result. 

The  above-mentioned  plan  is  much  used  in  Europe  to 
plant  tubers  from  \\  to  2\  inches  in  diameter  without 


154  TJie  Potato 

cutting.  Trouble  with  soil  diseases  affecting  the  stand 
is  causing  the  use  of  similar  small  seed  in  some  of  the 
western  potato-growing  sections.  The  use  of  small  culls 
as  seed  is  usually  condemned  in  the  United  States.  Very 
often  the  vitality  of  the  cull  seed  is  low  on  account  of 
disease  or  degeneration  in  the  parent  hill.  Many  experi- 
ments have  generally  resulted  in  higher  yields  from  use 
of  large  seed  cut  than  from  small  uncut  seed.  Even  if 
the  small  seed  is  used  on  part  of  the  field  on  account  of 
the  lower  cost,  it  will  pay  growers  in  the  northern  states  to 
have  seed  plots  in  which  large  cut  seed  is  planted.  While 
the  results  of  the  many  experiments  of  the  cutting  and 
size  of  seed  are  often  conflicting  some  general  rules  may 
be  stated :  — 

(1)  The  yield  to  the  acre  increases  with  the  size  of  the 
seed  piece  up  to  50  or  more  bushels  of  seed  to  the  acre 
when  the  distance  of  planting  is  the  same. 

(2)  The  yield  to  the  acre  increases  with  the  size  of  the 
fraction  of  the  seed  tuber  from  one  eye  up  to  the  whole 
large  tuber. 

(3)  The  net  yield  to  the  acre  above  the  amount  of  seed 
planted  and  the  increased  value  of  seed  potatoes  kept  till 
spring  compared  with  an  equal  number  of  bushels  on 
increased  yield  which  must  yet  bear  the  expense  of  digging, 
storage  and  marketing,  reduce  the  size  of  the  most  profit- 
able seed  to  plant  to  much  smaller  size. 

(4)  Increasing  the  number  of  hills  to  the  acre  to- 
gether with  the  amount  of  seed  used,  while  keeping 
the  size  of  the  seed  constant,  increases  the  total  yield 
and  reduces  the  yield  of  the  individual  hill  and  the  size 
of  the  tubers. 

(5)  Cutting  the  same  weight  of  seed  to  an  acre  into 
smaller  pieces  may  or  may  not  increase  the  yield  because 


Planting  155 

the  seed  will,  at  some  size,  be  cut  too  small  to  insure  a 
good  start  to  the  plants. 

(6)  As  noted  above,  salable  tubers  used  as  seed  usually 
outyield  cull  seed,  because  of  the  fact  that  a  larger  portion 
of  the  culls  come  from  weak,  diseased  or  degenerate  hills. 
The  cull  is  not  poor  seed  because  small,  but  because  there 
is  a  greater  chance  that  its  inherited  vigor  is  low.  In 
cool  and  wet  climates,  like  those  of  Scotland,  Ireland, 
and  Maine,  there  is  less  risk  of  small  seed  being  injured 
in  vigor  than  in  climates  too  hot  and  dry  for  the  best 
growth  of  the  potato.  The  use  of  the  systems  of  field 
seed  selection  to  find  the  strain  having  the  greatest 
inherited  vigor  with  seed  plots  to  multiply  the  selected 
seed  produced  a  stock  of  which  the  small  culls  may  be 
saved  for  use  as  seed. 

Experiment  stations  have  found  conflicting  results  in 
studying  the  relative  value  of  eye  in  different  parts  of  the 
tuber,  which  need  further  investigation.  The  eyes  at  the 
seed  end  of  the  tuber  start  first  to  grow  and  are  practically 
the  only  ones  which  grow  under  greening  in  the  sunlight. 
When  these  seed-end  eyes  start  sprouts,  which  are  broken 
off  in  handling  before  the  others  start  the  vigor  is  likely 
to  be  more  equal.  Observations  indicate  that  the  eyes 
nearest  the  stem  end,  particularly  with  varieties  having 
few  eyes  as  the  Rural  type,  are  the  ones  most  likely  to 
fail  to  grow  and  are  the  ones  from  which  degenerate 
strains  originate.  Under  the  present  state  of  knowledge 
of  the  subject,  it  is  safest  for  growers  to  cut  seed  in  such 
ways  as  to  have  the  seed  end  eye  on  as  many  of  the  cut 
pieces  as  possible,  and  to  allow  a  slightly  larger  amount 
of  flesh  to  the  pieces  with  stem  end  eye,  to  make  up  for 
their  slower  starting  growth  in  spring. 

Smaller  seed  pieces  can  be  used  with  fertile  soil  than 


156  The  Potato 

with  poor  soil.     The  young  plant  can  become  established 
and  get  its  nourishment  from  the  soil  quicker. 

Whole  seed  matures  the  crop  a  few  days  earlier,  an 
advantage  for  early  high  prices,  and  is  less  likely  to  rot 
in  cold  weather,  and  to  attacks  from  soil  diseases,  as  in 
Colorado. 

Cutting  seed 

Many  tools  have  been  invented  for  cutting  seed  potatoes, 
but  none  is  able  to  do  as  good  work  as  the  knife,  eitht  r 
in  the  hand  or  fastened  in  some  way.  The  Colorado 
cutting  rack  is  a  box  on  legs  with  slanted  or  sloping  bot- 
tom, having  an  opening  at  the  side.  To  the  rim  of  a 
ledge  at  the  front  of  the  operator,  a  knife  is  fastened 
with  the  point  vertical.  The  seed  rolls  through  the  ad- 
justable opening  at  the  side  to  the  ledge.  The  operator 
picks  up  the  seed  without  motion  except  that  of  his  hand 
and  wrist  and  cuts  the  seed  by  pulling  against  the  knife. 
Some  operators  prefer  to  push  against  the  knife,  but  the 
pulling  motion  is  better  because  the  eyes  are  then  always 
in  view,  and  better  judgment  can  be  used  in  allotting  the 
eyes  to  the  different  pieces  from  each  potato.  The  cut 
pieces  drop  into  a  crate  or  sack.  Trouble  with  potato 
diseases  of  the  seed  makes  it  always  advisable  to  have 
some  means  of  disinfecting  the  cutting  knives,  even  if 
the  seed  is  soaked,  as  no  treatment  reaches  into  the  in- 
terior of  the  tuber.  All  seed  suspected  of  being  danger- 
ously diseased  should,  of  course,  be  thrown  away.  A 
dish  of  formaldehyde  solution  in  which  to  disinfect  the 
knife  is  advisable.  Corrosive  sublimate  solution  is  a 
better  disinfectant,  but  is  a  very  dangerous  poison  to  have 
around. 

With  the  Colorado  cutting  rack,  the  operator  can  do 


Planting  157 

even  better  work  than  with  the  knife  hekl  in  the  hand 
and  can  cut  nearly  or  twice  as  fast  with  less  fatigue,  due 
to  the  fact  that  there  is  no  lost  motion  in  reaching  some 
distance  for  every  potato  cut.  All  roll  down  to  within  a 
few  inches  of  the  hand.  The  cost  is  small,  being  only 
that  of  a  little  rough  lumber,  as  the  knives  can  be  used 
for  other  purposes.  A  knife  may  be  held  by  fastening  to 
a  board  and  potatoes  picked  from  a  crate.  Any  knife 
used  in  cutting  seed  should  be  ground  thin  and  kept 
very  sharp. 

Under  most  conditions  a  larger  yield  is  secured  by 
planting  as  fast  as  the  seed  is  cut.  The  reduction  of  yield 
of  seed  allowed  to  dry  may  be  heavy.  Lack  of  labor  in 
planting  time  often  leads  farmers  to  cut  seed  in  periods 
of  bad  weather  and  to  save  the  time  of  cutting  later.  To 
prevent  the  loss  of  seed  by  heating,  it  should  be  kept  in 
separated  containers,  as  sacks  or  crates,  with  a  small 
amount  in  each  in  a  cool  place.  The  moisture  on  cut  sur- 
faces must  be  dry  to  prevent  heating  and  rot,  but  no  more 
drying  should  be  allowed.  Such  carefully  dried  cut  seed 
may  do  better  than  freshly  cut  in  cold  and  wet  soil. 
Land  plaster  (gypsum)  may  be  used  to  dry  cut  seed. 
Sulphur  has  been  advocated  for  disease-prevention,  but 
its  use  does  not  completely  prevent  any  disease  and  it 
is  very  disagreeable  to  handle. 

The  principles  of  seed  cutting  are  as  follows :  — 

(1)  Seed  pieces  should  be  cut  blocky  in  shape  to 
make  surfaces  as  small  as  possible.  Blocky  pieces  feed 
better  through  machine  planters  and  the  smaller  exposed 
cut  surface  reduces  loss  of  moisture  and  danger  of  infec- 
tion by  rot  germ  (see  Plate  VIII). 

(2)  The  probability  in  most  cases  that  the  seed  and 
eyes  are  more  vigorous  makes  it  better  to  cut  each  tuber 


158  The  Potato 

in  such  shaped  pieces  that  will  give  the  largest  number 
having  eyes  from  the  seed  end.  Seed  of  size  to  make  two 
pieces  should  be  halved  through  center  of  seed  end  group 
of  eyes.  Tubers  short  and  round  enough  to  make  four 
pieces  without  their  being  too  long  and  slender  should  be 
quartered  through  the  seed  end  group.  Those  which 
will  make  too  slender  quarters  cut  in  this  way  should  be 
cut  once  lengthwise  and  then  transversely,  making  four 
blocky  pieces.  Many  tubers  will  be  the  right  size  and 
weight  to  furnish  three  seed  pieces.  These  should  be 
cut  with  one  piece  taken  off  the  stem  end  about  one-third 
of  the  length  from  the  stem  and  the  remainder  of  the 
tuber  halved  through  the  seed  end  group  of  eyes.  This 
gives  two  out  of  tliree  pieces  with  a  more  vigorous  seed 
end  eye  and  the  third  being  cut  with  a  little  more  flesh 
to  make  up  for  the  slower  start  given  by  its  eyes  compared 
with  those  of  the  seed  end. 

Fairly  blocky  seed  large  enough  for  six  pieces  is  cut  in  a 
similar  way,  splitting  the  stem  end  into  two  pieces  and 
the  seed  end  into  four.  Seed  cutting  into  more  than 
six  pieces  often  has  so  few  eyes,  compared  with  the  amount 
of  flesh,  that  it  is  difficult  to  cut  well,  especially  towards 
the  stem  end.  The  seed  end  of  such  large  seed  should 
usually  be  cut  into  four  pieces. 

(3)  To  make  sure  of  one  good  eye  on  every  seed  piece, 
it  is  well  to  have  two  wherever  possible. 

(4)  The  average  weight  of  the  seed  must  be  adjusted 
to  the  needs  of  the  crop  for  the  soil  planted.  Garden 
soils  will  need  little  more  than  the  eye  itself  to  produce 
plants,  while  soils  in  very  poor  condition  need  large  seed 
to  furnish  nourishment  to  the  young  growing  plant  for 
some  time  before  it  can  grow  roots  far  enough  to  support 
itself.     The  commonest  size  of  seed  used  runs  from  one 


Planting  159 

to  two  ounces.  The  average  amount  of  seed  used  to  the 
acre  in  America  is  estimated  at  11  to  12  bushels,  the 
range  in  most  cases  being  from  9  to  16  bushels.  Under 
European  conditions,  growers  find  it  profitable  to  plant 
larger  amounts.  In  England  a  long  ton,  or  about  37 
bushels  to  the  acre,  is  the  usual  amount  and  is  often 
exceeded. 


CHAPTER  VIII 

CARE  OF  THE  GROWING  CROP 
By  Daniel  Dean 

The  tillage  of  the  potato  crop  is  best  considered  as  a 
connected  whole  from  the  time  of  plowing  until  the  last 
cultiv^ation.  The  results  of  tillage  before  planting  and 
after,  in  rendering  soil  fertility  available,  in  conserving 
moisture  and  in  killing  weeds  are  the  same.  There  is  no 
danger  of  injury  to  the  growing  plant  before  planting. 
Therefore,  as  large  a  part  of  the  tillage  of  the  potato  as 
practicable  should  be  done  before  planting.  If  soil 
moisture  has  been  well  conserved,  plant-food  made  avail- 
able and  a  large  part  of  the  weeds  in  the  soil  killed,  the 
amount  of  the  tillage  after  planting  can  be  largely  reduced. 
The  danger  of  injury  to  the  plants  can  thus  be  largely 
prevented.  The  cost  of  tillage  with  wide  tools  like  the 
harrows  is  less  than  that  of  work  between  rows.  Only 
careful  men  can  be  trusted  to  work  tools  between  rows 
without  danger,  while  much  poorer  labor  can  work  in  the 
open  field.  When  plowing  is  delayed  until  just  before 
planting,  a  dry  period  following  will  badly  injure  the  crop. 

Tillage  is  most  profitable  when  given  at  one  particular 
time.  After  every  rain  the  soil  is  at  first  too  wet  and  stiff 
to  work  without  injury.  It  should  be  carefully  watched 
until  in  the  driest  part  of  the  field  it  becomes  mellow 
enough  to  work.  At  this  stage,  the  soil  crumbles  easily 
160 


Care  of  the  Growing  Crop  161 

and  has  passed  the  time  at  which  stirring  will  cause  baking. 
Stirring  the  soil  at  this  time  saves  the  maximum  amount 
of  moisture  for  the  use  of  the  growing  crop.  Evaporation 
is  so  rapid  that  a  few  hours'  delay  results  in  a  great  loss  of 
water.  The  air  is  usually  cool  and  the  soil  stirs  easily. 
With  fresh  horses,  a  large  area  can  be  covered  in  a  few 
hours.  Weed  seeds  which  have  been  sprouted  by  the  re- 
cent rains  are  stirred  about  and  the  weeds  killed.  Grow- 
ing weeds  which  have  escaped  previous  cultivation  are 
torn  out  and  left  on  top  of  the  soil  to  be  dried  and  killed 
by  the  heat  of  the  sun.  The  potato  plants  have  just 
received  the  stimulation  of  needed  rain  and  the  dissolved 
plant-food  which  has  been  forming  in  the  soil  during  dry 
weather  but  not  available  on  account  of  lack  of  moisture. 
Under  these  conditions,  the  potatoes  can  stand  root 
injury  which  would  be  more  dangerous  at  drier  times. 

Wide  tools  can  be  used  in  tillage  nearly  up  to  the  time 
the  sprouts  break  through  the  surface  of  the  soil.  The 
common  practice  in  the  principal  potato-growing  states, 
outside  of  Maine,  of  harrowing  down  the  ridges,  left  by 
the  planter  or  by  ridging  tools  after  planting,  is  very 
beneficial.  Plank-floats  or  clod-crushers  are  often  used, 
but  they  are  dangerous  to  the  growing  sprouts.  The 
ideal  tool  for  this  purpose  would  be  a  level  which  would 
smooth  down  the  ridges  without  crushing  the  soil  around  the 
sprouts.  A  tool  made  of  plank  2  X  10  inch  standing  on 
edge  and  long  enough  to  cover  two  rows,  has  been  found 
very  useful.  The  driver  stands  on  a  horizontal  plank 
fastened  to  the  rear  of  the  plank  which  does  the  work. 
According  to  the  hardness  of  the  soil,  the  vertical  plank 
is  slanted  slightly  or  dropped  below  the  level  of  the  hori- 
zontal plank.  Frequent  adjustment  is  needed  as  the  soil 
changes  texture  rapidly  after  rains.     The  horse  should  be 


162  TJie  Potato 

hitched  close  to  the  level  to  keep  it  from  digging  into  the 
soil.  On  any  but  perfectly  level  fields,  the  use  of  level  or 
harrow  on  more  than  two  rows  at  a  time  is  likely  to  result 
either  in  injury  from  working  one  row  too  deeply  or 'in 
poor  work  from  going  too  shallow  on  one  and  hurting  the 
others.  Leveling  the  rows  can  be  delayed  longer  when  the 
seed  is  covered  deeply.  Many  stones  in  the  soil  make  it 
advisable  to  level  earlier  if  it  can  be  done  at  all  on  account 
of  stones  moving  the  seed. 

A  practice  used  much  in  IVIaine  and  suited  to  wet  and 
cold  climates  is  to  ridge  the  potato  rows  just  after  the 
plants  come  up.  If  frost  follows,  the  plants  are  safe  from 
it  for  several  days  longer  than  if  left  uncovered.  Such 
ridging  kills  many  weeds,  but  is  suited  only  to  sections  in 
which  the  soil  is  sure  not  to  bake  over  the  little  plants,  and 
to  conditions  of  damp  soil  which  make  ridging  the  best 
practice. 

Without  heavy  ridging  late  in  the  season,  the  weeds 
hardest  to  control  are  those  closest  to  the  potato  plants. 
Thorough  stirring  before  the  plants  come  up  and  a  fre- 
quent use  of  the  weeder  afterwards  enables  one  to  control 
the  weeds  near  the  plants  as  easily  as  those  between  the 
rows. 

Many  forms  of  cultivators  are  made  for  tilling  the  soil 
between  the  rows  of  potatoes.  Very  heavy  soils,  such  as 
those  of  the  Greeley  region  of  Colorado,  need  four-horse 
cultivators  which  use  two  teeth  four  inches  wide  and  four- 
teen inches  long  on  each  side  of  the  row  and  stir  the  heavy 
clay  to  the  depth  of  eight  or  ten  inches.  Other  cultivators 
for  light  sandy  soils  may  merely  stir  the  surface  with  twelve 
or  fourteen  peg  teeth.  Between  these  types,  every  grada- 
tion of  size  and  number  of  teeth  may  be  found  according  to 
the  soil  conditions. 


Care  of  the  Growing  Crop  163 

As  a  general  rule  the  first  cultivation  after  planting  is 
made  as  deep  and  as  close  to  the  seed  as  possible,  because 
the  potato  roots  have  not  started  far  yet  and  are  safe  from 
injury.  The  soil  settles  together  so  quickly  that  it  should 
be  kept  mellow  in  this  way  as  long  as  possible.  Sometimes 
a  second  deep  cultivation  may  be  given.  Later  cultiva- 
tions after  the  roots  start  are  made  with  the  teeth  working  as 
shallow  as  they  can  be  made  to  work,  so  as  to  form  a  mellow 
soil  mulch.  This  depth  will  vary  in  different  soils  from  one 
to  three  inches.  ]\Ieasurement  will  show  that  cultivator 
teeth  often  work  much  deeper  than  the  grower  is  aware. 
As  the  tops  begin  to  grow  and  form  a  mass,  the  cultivator 
teeth  can  be  narrowed.  Weeds  start  less  in  the  shade  of 
the  tops  and  evaporation  becomes  less,  partly  on  account 
of  the  shade  and  partly  because  surface  roots  form  to  use 
the  moisture.  Wide,  deep  teeth  are  manufactured  to 
cut  the  roots  of  perennial  weeds  like  the  Canada  thistle. 
Such  teeth  may  often  be  substituted  in  part  for  the  com- 
mon teeth.  Cultivators  are  made  for  one,  two,  three  or 
four  horses,  with  wdieels  and  without,  and  for  the  driver 
to  walk  or  ride.  One-horse  walking  cultivators,  common 
in  the  East  and  South,  have  great  disadvantages.  Even 
when  fitted  with  wheels  in  front  to  regulate  the  depth,  the 
teeth  cut  much  deeper  in  some  soils  than  in  others.  The 
machine  is  too  light  to  hold  in  the  soil  in  stony  ground. 
Masses  of  weed  roots,  like  those  of  quack-  or  witch-grass, 
clog  the  teeth  and  cause  the  teeth  to  rise  out  of  the  soil  at 
the  very  places  where  the  best  work  is  needed.  Wheel 
cultivators  enable  one  to  regulate  the  depth  of  working  to 
better  advantage.  The  weight  of  the  wheel  cultivators, 
with  that  of  the  driver,  holds  the  teeth  into  the  ground 
among  stones  and  weeds.  The  wheels  prevent  the  teeth 
from  cutting  too  deeply  in  mellow  places  free  from  weeds. 


164  The  Potato 

Deep  cultivation  is  most  dangerous  in  dry  times.  The 
gain  from  weed  killing  may  be  offset  by  the  loss  of  the 
potato  roots. 

A  tool  which  is  used  less  than  it  should  be  is  the  weeder. 
Weeds  like  ragweed,  foxtail  or  barn  grass,  pigweed  and 
the  whole  class  which  grow  from  small  seeds  in  the  potato 
field  are  very  easily  killed  by  the  frequent  use  of  the  weeder 
until  the  potatoes  are  nearly  a  foot  high.  Weeders  are 
made  with  either  two  or  three  rows  of  teeth,  with  wheels 
and  without  and  Avith  different  styles  of  teeth.  The  prin- 
ciple is  the  same  in  all,  that  the  light  and  somewhat  flexible 
teeth  tear  out  and  destroy  the  tiny  weeds  starting  in  the 
surface  soil  with  little  or  no  injury  to  the  larger  sized  potato 
vines.  The  weeder  is  a  tool  which  demands  certain  soil 
conditions  to  be  effective.  It  will  not  work  at  all  on  hard 
soil.  Many  growers  have  discarded  weeders  after  trying 
them  where  the  soil  was  not  suited  to  their  use.  Most 
soils  have  a  short  period  after  every  rain  when  the  flexible 
weeder  teeth  are  able  to  penetrate  and  stir  the  soil.  If 
that  time  is  taken  for  their  use,  many  sprouting  weeds 
can  be  killed  in  a  very  short  time  and  the  surface  mulch 
established  close  to  the  potato  plant.  The  weight  of  the 
weeder  selected  and  the  stiffness  of  the  teeth  should  be 
carefully  chosen  according  to  the  character  of  the  soil.  If 
necessary,  weight  can  be  added.  A  needed  precaution  in 
the  use  of  the  weeder  is  to  keep  the  teeth  free  from  trash. 
Weeders  are  often  used  to  follow  a  cultivator  with  large 
teeth  to  better  level  the  soil  between  the  rows.  Weeders 
and  leveling  tools,  like  the  harrow,  are  sometimes  driven 
crossways  of  the  potato  row.  It  may  be  possible  to  do 
the  work  a  little  better  in  this  way,  but  the  danger  of  injury 
to  the  growing  sprouts  and  roots  of  the  potatoes  from 
crushing  under  the  feet  of  the  horses  is  so  great  that  it  is  a 


Care  of  the  Growing  Crop  165 

practice  of  doubtful  advantage.  In  most  cases,  practically 
all  of  the  weeds  can  be  killed  by  driving  along  the  row. 
The  weeder  is  a  tool  for  prevention  of  weeds  rather  than 
their  cure.  It  will  not  kill  those  which  have  got  much  of  a 
start  above  the  soil  or  those  with  underground  rootstocks 
like  quack-grass. 

A  comparison  of  potato-growing  of  1916  with  that  of  50  to 
75  years  ago  shows  how  great  has  been  the  substitution  of 
tools  operated  by  the  power  of  animals  for  those  worked  by 
man.  Where  formerly  the  plow  and  harrow  were  nearly 
the  only  tools  not  worked  by  hand  labor,  the  farmer  may 
now  use  the  horse-drawn  planter,  fertilizer-sower,  manure- 
spreader,  numerous  types  of  cultivators,  weeders,  ridgers 
and  other  tillage  tools,  the  sprayer  and  the  different  types 
of  diggers. 

Within  the  last  twenty  years  the  gasoline  engine  has 
been  developed  to  a  wonderful  degree.  Millions  have  been 
built  for  automobiles  and  probably  millions  more  have 
been  sold  for  farm  use,  for  threshing,  feed  grinding,  pump- 
ing water  and  other  uses.  Gasoline  tractors  are  being 
rapidly  developed  to  draw  farm  tools  in  the  field.  As  yet 
they  have  been  little  used  in  potato-growing  except  for 
plowing  and  harrowing.  A  great  obstacle  to  the  use  of 
present  tractors  between  potato  rows  is  the  width  of  a  track, 
usually  four  or  five  feet.  Potato  rows  are  usually  about 
three  feet  apart  and  tools  for  work  between  the  rows  must 
have  a  tread  of  about  three  feet,  or  else  have  a  six-foot 
tread,  like  most  potato  sprayers.  Four-wheeled  tractors 
used  to  draw  tools  need  two  operators,  one  for  the  tractor 
and  another  to  handle  the  tools.  On  any  but  perfectly 
level  land  the  side  movements  of  front  or  rear  wheels  in 
skidding  quickly  injure  the  potato  plant.  New  types  of 
tractors  are  being  developed  by  which  the  same  two  wheels 


166  The  Potato 

are  used  for  driving  and  steering,  the  tool  itself  taking  the 
place  of  the  other  wheels  of  the  tractor.  One  operator 
handles  both  engine  and  tools.  Similar  small  engine- 
propelled  tools  are  being  made  for  garden  use. 

Engines  are  being  used  on  potato  sprayers  to  give  better 
results  by  higher  pressures  than  horses  can  furnish.  The 
elevating  and  separating  machinery  of  potato  diggers  is 
sometimes  driven  by  engines,  horses  being  used  to  draw 
the  tool  only. 

Harrows  or  leveling  tools  are  usually  used  once ;  occa- 
sionally twice.  Weeders  may  be  used  up  to  a  dozen  times 
in  extreme  cases  and  half  a  dozen  pay  well.  Cultivators 
are  used  from  three  to  eight  times  with  four  or  six  as 
the  most  common  number.  Outside  of  Maine,  the  ridging 
tools  are  used  once  or  twice.  Thorough  tillage  and  a  good 
condition  of  the  soil  before  planting  necessitate  less  work 
later.  It  is  a  good  rule  to  cultivate  after  every  heavy 
rain,  and  to  cultivate  more  frequently  in  hard  soils  than  in 
light.  Tillage  is  less  needed  in  soils  which  are  mellow  and 
full  of  organic  matter,  because  such  soils  supply  plant-food 
and  water  more  readily. 

The  danger  of  the  growing  tubers  protruding  out  of  the 
soil  and  being  sunburned  is  prevented  by  ridging  lightly 
after  the  tubers  are  formed.  Ridging  earlier  does  not  pre- 
vent sunburn  because  the  depth  at  which  the  tubers  form  is 
controlled  by  the  depth  of  planting.  Very  shallow  plant- 
ing results  in  the  tubers  forming  below  the  seed  and  very 
deep  planting  in  forming  at  a  depth  where  little  sunburn- 
ing  results.  Usual  depths  of  planting  are  not  deep  enough 
to  entirely  prevent  sunburn.  While  late  ridging  is  some- 
what feasible,  the  difficulty  is  that  any  injury  to  the  roots 
of  the  growing  potato  plant  at  that  stage  is  dangerous. 

Tillage  is  so  necessary  in  potato-growing  for  the  libera- 


Care  of  the  Growing  Crop  167 

tion  of  plant-food,  maintenance  of  healthful  soil  conditions, 
saving  moisture  and  weed  killing  that  it  must  be  practiced 
after  planting  the  potato  crop.  As  the  potato  plants  are 
more  tender  than  most  weeds,  great  injury  may  result  from 
careless  tillage.  The  tender  white  sprouts  starting  from 
the  seed  tubers  are  usually  injured  by  a  touch.  The  soil 
about  the  seed  may  be  thoroughly  stirred  with  a  harrow 
and  level  during  the  first  few  days  after  planting  without 
danger.  The  weeder  can  be  used  with  good  results  in 
killing  weeds  and  keeping  a  soil  mulch  above  the  plants 
if  great  care  is  used  to  prevent  the  teeth  from  injuring  the 
sprouts.  If  the  number  of  injured  sprouts  is  small,  the  gain 
from  the  tillage  may  outweigh  the  setback  which  the  in- 
jured plants  receive. 

The  next  period,  from  the  time  the  plants  form  green 
leaves  above  the  ground  till  the  tops  are  eight  to  twelve 
inches  high,  is  one  when  the  benefits  of  tillage  are  usually 
greater  than  possible  injury.  During  a  large  part  of  the 
time  the  plant-food  in  the  seed  tubers  is  still  available,  and 
the  leaf  surface  is  not  yet  large  enough  to  transpire  enough 
water  to  seriously  injure  the  plant.  Sun-scald  and  tip- 
burn  are  not  common  imtil  the  plants  are  larger.  Roots 
are  being  developed  close  around  the  seed  and  stalks. 
Until  the  roots  are  numerous  enough  for  tillage  to  destroy 
more  than  a  small  proportion  of  the  whole  root  system, 
tillage  is  beneficial.  Later  the  horizontal  roots  extend 
until  they  cross  between  the  rows.  These  roots  are  now  of 
the  size  to  make  their  injury  a  serious  matter  to  the  grow- 
ing plant.  The  greatest  development  of  the  roots  is  in 
the  plowed  area,  or  five  to  ten  inches  below  the  surface. 
Many  roots  also  extend  down  to  the  depth  of  three  to  four 
feet.  A  large  part  of  these  vertical  roots  drop  downward 
from  the  large  horizontal  roots  close  to  the  surface.      It  is 


168  The  Potato 

very  difficult  to  use  any  cultivator  or  ridging  tool  late  in 
the  season  without  cutting  these  lateral  roots.  The  loss 
of  root  area  is  further  increased  by  the  loss  of  the  vertical 
roots  attached  to  these  lateral  ones. 

The  relation  of  the  value  of  these  roots  to  the  yield  of 
the  crop  is  vital.  One  function  of  the  roots  of  the  growing 
plants  is  to  take  in  water  containing  plant-food  in  solution. 
The  water  is  transpired  from  the  lea\es  and  the  plant- 
food  transformed  into  material  for  further  growth  of  the 
plant.  Transpiration  from  the  leaves  of  the  potato  is  less 
easily  checked  in  periods  of  drought  than  with  many  other 
plants.  The  potato  has  less  ability  to  regulate  its  use  of 
w^ater  by  the  supply  available.  Removing  part  of  the 
leaves  by  pruning  or  by  attacks  of  disease  reduces  the  yield 
by  taking  away  from  the  plant  the  factory  in  which  the 
material  for  the  tubers  is  elaborated.  As  the  supply  of 
water  and  plant-food  remains  the  same,  such  pruning  may 
even  be  of  benefit  in  the  cases  where  the  normal  food 
supply  is  deficient.  The  removal  of  part  of  the  roots  not 
only  removes  a  fraction  of  the  supply  of  water  and  food, 
but,  from  the  nature  of  the  plant,  throws  it  out  of  balance. 
The  leaves  continue  to  transpire  water,  and  in  the  lack  of 
full  supply  from  the  root,  use  up  part  of  the  water  in  the 
plant  itself.  The  whole  plant  suffers,  the  greatest  injury 
showing  at  the  tips  of  the  leaves.  The  ends  of  the  leaves 
dry  up  and  die,  a  trouble  commonly  called  "tip-burn." 

The  strain  upon  the  potato  from  exhausting  effects  of 
blossoming  and  forming  tubers  at  nearly  the  same  time  is 
very  heavy.  The  heat  and  drought  which  often  occur  at 
this  time  add  to  the  troubles  of  the  plants.  Any  damage 
to  the  plant  is  now  more  dangerous  than  before.  At  this 
time,  tillage  may  be  beneficial  or  may  be  very  injurious. 
If  the  weather  is  cool  and  the  soil  water  ample,  tillage  may 


Care  of  the  Growing  Crop  169 

gret.tly  increase  the  crop.  Hot  and  dry  weather,  at  or 
following  the  time  of  tillage,  may  nearly  ruin  the  crop, 
weakened  by  root  injury. 

Tillage  so  loosens  the  upper  inches  of  the  soil  that  the 
roots  cannot  de\'elop  there  until  after  tillage  stops.  The 
plant-food  contained  therein  may  be  of  great  value  to  the 
growing  crop.  Exhaustive  experiments  show  that  with 
corn  practically  the  same  amount  of  water  is  found  in  the 
soil  late  in  the  season  whether  tilled  or  not.  The  plant 
roots  are  able  to  use  the  water  before  it  can  escape  from  the 
surface.^  If  weeds  have  been  killed,  there  is  little  need  of 
stirring  the  soil  late  in  the  season.  The  frequent  grinding 
of  the  upper  soil  layer  by  early  tillage  has  changed  much 
of  its  contained  plant-food  into  a  condition  in  which  it  is 
available  to  the  plants.  If  the  previous  care  has  been  such 
that  the  crop  has  passed  the  critical  period  in  good  condi- 
tion, the  roots  soon  fill  the  surface  soil  and  use  the  plant- 
food  supply  for  the  production  of  tubers.  A  few  weeds 
which  may  have  escaped  the  tillage  tools  should  be  pulled 
by  hand  in  July  and  August  before  they  go  to  seed. 

Spraying  is  commonly  thought  of  only  in  its  relation  to 
insects  and  diseases.  Thorough  spraying  with  bordeaux 
has  been  found  to  give  an  increase  in  yield  in  the  absence 
of  disease  and  insects.  This  action  is  noted  most  in  hot 
and  dry  seasons.  It  should  always  be  considered  among 
the  methods  to  insure  good  yields  in  sections  where  heat 
and  drought  are  likely  to  limit  the  yield. 

1  111.  Bui.  181.     Bui.  257,  Bur.  PI.  Ind.,  U.  S.  Dept.  Agr. 


CHAPTER  IX 

POTATO  INSECTS  AND   THEIR  CONTROL 

The  amount  of  damage  to  the  potato  crop  by  insects 
is  very  large,  much  larger  than  is  ordinarily  supposed. 
Spraying  with  poisonous  substances  has  to  be  resorted  to 
in  order  to  obtain  a  crop  which  has  been  uninjured  by 
insects.  They  do  four  kinds  of  damage  and  may  be  clas- 
sified in  this  manner:  (1)  insects  chewing  the  leaves; 
(2)  insects  sucking  the  leaves  and  tips ;  (3)  stalk  borers ; 
and  (4)  insects  affecting  the  tubers.  Most  of  the  damage 
is  done  by  the  Colorado  potato-beetle  and  the  flea-beetle. 

The  Colorado  jJotato-beeUe  {Leptinotarsa  decemlineata) 
(Fig.  10). 

This  is  a  leaf-eating  insect,  and  its  ravages  are  very 
general.  It  seems  to  be  always  present  where  potatoes 
are  grown,  and  the  damage  it  causes  is  very  great.  Indeed, 
in  most  sections,  it  is  impossible  to  obtain  a  crop  at  all 
unless  its  ravages  are  held  in  check  by  the  application  of 
some  poisonous  substance  to  the  leaves. 

This  insect  is  a  native  of  a  strip  of  country  which  lies 
just  east  of  the  Rocky  Mountain  range  and  includes  eastern 
Colorado.  In  its  native  state  the  beetle  lives  upon  the 
wild  weeds  of  the  potato  family,  the  chief  of  which  is  the 
sandbur  (*S.  rostratum).  It  is  a  general  feeder,  living  on 
170 


Potato  Insects  and  their  Control  171 

not  only  potatoes,  but  tomatoes,  eggplants,  tobacco  and 
peppers. 

"It  was  first  brought  to  notice,"  says  Geo,  C.  Butz, 
"about  the  year  1856.  In  1861  it  was  found  in  the  potato 
fields  of  the  settlers  of  Kansas.  In  1862  it  was  in  Iowa,  and 
in  1862  it  appeared  in  southwestern  Wisconsin.  It  crossed 
the  Mississippi  River  into  Illinois  in  1864.  It  was  in 
Michigan  and  Indiana  in  1867,  Ohio  in  1868  and  Pennsyl- 
vania in  1870.  It  moved  eastward  at  the  rate  of  about  fifty 
miles  a  year  for  a  number  of  years,  but  later  it  traveled 
more  rapidly.  It  is  reported  to  have  reached  the  Atlantic 
Coast  about  1874,  and  Nova  Scotia  about  1882.  When  it 
reached  the  Atlantic  Coast,  it  had  traveled  1500  miles  in 
sixteen  years,  and  nearly  1000  miles  more  the  next  eight 
years  in  its  march  to  Nova  Scotia." 

The  mature  beetle  hibernates  in  winter  in  the  ground 
usually  at  a  depth  of  eight  to  ten  inches  and  begins  to  fly 
early  in  the  spring.  As  soon  as  the  first  leaves  of  the  po- 
tato appear  above  the  ground,  the  beetles  fly  to  them  and 
soon  lay  their  reddish  yellow  or  orange-colored  eggs  in 
clusters  on  the  under  side  of  the  leaves.  In  about  a 
week  the  young  beetles  or  larvae  appear  and  begin  to 
devour  the  foliage  with  great  rapidity.  The  larvae 
pass  through  four  stages  or  instars  and  are  mature  in 
sixteen  to  twenty-one  days,  according  to  the  weather. 
Then  they  go  into  the  ground  and  transform  into  the  pupa 
or  resting  stage,  in  which  they  remain  at  least  a  week  — 
usually  longer  —  before  coming  out  as  the  adult  beetles. 
The  egg-laying  period  lasts  about  thirty-five  or  forty  days. 
The  minimum  time  for  the  life  cycle  is  about  four  weeks. 
The  last  brood  of  larvae  which  disappear  into  the  soil 
before  severe  frost  pupate  there,  remaining  in  the  ground 
in  the  form  of  perfect  insects  until  the  following  spring. 


172  The  Potato 

The  adult  beetle  is  oval  in  shape,  about  three-eighths  of 
an  inch  in  length  and  a  trifle  narrower  than  long.  The 
ground  is  yellow  and  the  wings  are  marked  by  ten  black 
lines  running  lengthwise.  There  are  also  black  markings 
on  the  thorax  (see  Fig.  10).  These  insects  have  great 
power  of  endurance.  They  will  walk  for  great  distances  in 
search  of  food,  and  it  is  said  by  direct  experiment  they  are 
known  to  have  lived  thirty  days  without  food.  Their 
eggs  are  a  bright  yellow  when  fresh  and  the  young  are 
dark  red  or  brown  grubs  with  black  heads  and  markings 
of  black  spots  in  double  rows 
on  each  side.  The  color  be- 
comes lighter  as  the  grubs 
mature. 

Control.  —  The      Colorado 
potato-beetle  is  controlled  by 
the    use    of    poisonous    sub- 
*  ^  stances  which  either  in  solu- 

FiG.  10.     Potato  bug,  larva  and      ,•  •  i 

mature  beetle  enlarged.  tion  or  suspension  are  sprayed 

upon  the  vines.  The  most 
common  of  these  arsenical  poisons  are  paris  green,  arsenate 
of  lead  or  arsenate  of  soda.  Any  one  of  them  may  be 
sprayed  upon  the  vines  alone  or  mixed  with  bordeaux  mix- 
ture and  applied.  Poison  is  usually  necessary  only  for  the 
first  two  regular  sprayings,  but  should  be  added  at  any  time 
the  larvae  become  numerous.  The  eggs  should  be  watched 
carefully,  and  after  they  are  well  hatched  and  the  young 
have  begun  to  feed,  the  first  application  of  the  poison 
should  be  made.  A  second  spraying  will  doubtless  be 
necessary  in  ten  days  to  two  weeks.  The  necessity  for 
subsequent  applications  of  poison  will  be  determined  by 
any  later  appearance  of  the  pests.  The  first  sprayings 
should  not  be  delayed  too  long,  as  the  larvae  develop  very 


Potato  Insects  and  their  Control  173 

rapidly  after  hatching  and  much  harm  is  often  done  before 
one  is  aware  of  it.  With  fifty  gallons  of  water,  if  the  poison 
is  to  be  used  alone,  or  of  bordeaux  mixture,  use  three  to 
five  pounds  of  arsenate  of  lead  or  one  pound  of  paris  green, 
and  add  two  pounds  of  quicklime  to  prevent  burning. 
One  pound  of  paris  green  to  the  acre  in  either  water  or 
bordeaux  mixture  is  ordinarily  recommended.  Growers 
should  be  warned  against  the  use  of  excessive  quantities  of 
paris  green  because  it  burns  and  injures  the  vines  if  put  on 
too  strong.  Arsenate  of  lead  has  the  advantage  of  adher- 
ing to  the  vines  and  is  only  slightly  washed  off  by  rains. 
After  long-continued  rains,  the  vines  may  often  be  seen 
to  be  grayish  in  color  because  of  the  arsenate  still  clinging 
to  them.  When  these  poisons  are  applied  with  water, 
whether  with  or  without  bordeaux  mixture,  some  provision 
must  be  made  to  keep  them  constantly  agitated  so  that 
they  will  not  settle  to  the  bottom  of  the  spray  tank. 

Flea-beetle  {Epitrix  cucumeris)  (Fig.  11) 

This  is  a  leaf-eating  insect.  There  are  several  kinds  of 
flea-beetles  which  are  troublesome  to  potatoes,  the  one 
named  above  being  the  most  common.  In  the  South  the 
tobacco  flea-beetle  {Epitrix  parvula)  and  the  eggplant 
flea-beetle  {Epitrix  fuscnla)  do  considerable  damage. 
Another  larger,  more  elongated  form,  known  as  Systena 
hudsonias,  has  been  found  to  cause  considerable  damage 
in  the  North. 

These  flea-beetles  all  belong  to  the  leaf-chewing  class. 
The  adult  beetles  frequently  do  much  damage  to  the 
potato  crop,  but  being  so  small,  less  than  one-twentieth 
of  an  inch,  they  are  often  not  seen.  They  are  black  and 
jump  when  alarmed,  which  also  makes  it  difficult  to  see 


174  The  Potato 

them.  The  result  of  their  depredations  will  be  found  in 
the  many  small  holes  which  may  be  noticed  in  the  leaves 
of  the  young  potato  plants,  and  in  the  lessening  of  the 
crop  on  this  account.  These  many  small  holes  make 
excellent  starting  places  for  many  diseases  to  get  a  foot- 
hold to  injure  the  plant.  The  beetles  stay  mostly  on  the 
under  side  of  the  leaves  and  are  not  seen,  their  presence 
being  detected  only  by  their  work.  The  larvae  occasion- 
ally do  injury  by  mining  into  the 
tubers  and  cause  pimply  potatoes. 
During  the  hot,  dry  summers, 
especially,  they  often  become  the 
worst  enemies  of  the  potato.  The 
insects  very  often  congregate  in 
b  such  numbers  that  the  leaves  of  the 

Fig.  11.    Flea-beetle,       plants  appear  almost   black  with 
them.     Young  potatoes  and  newly 
set  tomato  plants  frequently  have  their  leaves  so  badly 
eaten  that  they  shrivel,  and  the  tomatoes  may  die. 

The  life  histories  of  the  different  flea-beetles  are  prac- 
tically the  same.  The  adult  insects  live  over  winter  under 
leaves  and  rubbish  and  appear  during  the  latter  part  of 
May  and  first  of  June.  As  soon  as  they  come  out,  they 
lay  eggs  near  the  roots  of  the  potatoes  or  of  weeds  related 
to  them.  The  larvae  mine  into  the  roots ;  and  when  full 
grown,  they  pupate  and  later  emerge  as  adult  flea-beetles. 
In  some  sections,  particularly  in  Colorado,  the  greatest 
damage  is  done  by  the  larvse,  which  are  tiny  white  grubs 
about  a  quarter  of  an  inch  in  length.  They  frequently  cut 
into  and  destroy  the  young  tuber  stems  of  the  potato  and 
prevent  a  regular  setting  of  the  crop. 

One  brood  of  potato  flea-beetle  appears  yearly  in  the 
North  and  two  broods  in  the  South,  the  second  ordinarily 


Potato  Insects  and  their  Control  175 

appearing  in  August  and  September.  This  brood,  coming 
at  a  time  when  the  tubers  are  partially  or  wholly  grown, 
bores  into  the  flesh  and  underneath  the  skin  of  the  potato, 
causing  a  pimply  or  scabby  appearance  which  detracts 
from  their  market  value. 

Control.  —  Flea-beetles  are  very  largely  controlled  by 
bordeaux  mixture,  which  acts  as  an  effective  repellant. 
They  ordinarily  feed,  however,  on  the  under  side  of  the 
leaves,  and  thorough  spraying  both  on  the  upper  and  lower 
sides  of  the  leaf  is  necessary  to  be  satisfactorily  effective. 
Spraying  may  have  to  be  begun  somewhat  earlier  for  the 
flea-beetle  than  for  other  insects  or  diseases.  The  insects 
are  so  small  and  their  damage  begins  on  the  under  side  of  the 
leaves,  so  that  often  a  great  amount  of  damage  may  have 
been  done  before  it  is  detected.  It  is  a  good  practice  to 
eliminate  from  the  farm  such  plants  of  the  solanacese  fam- 
ily as  nightshade,  bitter-sweet,  horse-nettles,  ground  cherry 
and  jimson  weed.  The  flea-beetles  breed  on  these  as  well 
as  the  potato  itself. 

Blister-beetle  {Epicauta  and  Macrobasis) 

These  are  leaf-eating  insects.  The  so-called  "blister- 
beetle"  or  "old-fashioned  potato-bug"  consists  of  four  or 
five  species  of  insects  which  do  a  tremendous  amount  of 
damage  to  the  potato  in  some  years.  They  sometimes 
appear  in  great  numbers  and  are  not  easily  vanquished. 
They  are  all  medium-sized  elongated  beetles  of  different 
colors :  spotted,  striped,  black,  light  or  dark  gray.  The 
adults  damage  the  potato  plant,  but  the  larvae  are  especially 
beneficial  in  destroying  the  egg  masses  of  the  grasshoppers. 

A  large  number  of  eggs  are  deposited  by  the  female  in  a 
small  cavity  in  the  ground.     The  larvae  are  provided  with 


176  The  Potato 

legs  by  which  they  crawl  about  until  they  find  a  grass- 
hopper's egg  mass,  upon  which  they  feed.  They  then  molt, 
their  legs  becoming  rudimentary.  As  helpless  grubs  they 
complete  the  remainder  of  their  larval  stage  surrounded 
by  an  abundance  of  food.     There  is  one  brood  a  year. 

Control.  —  If  potatoes  are  carefully  sprayed  for  the 
Colorado  potato-beetle  and  flea-beetle,  there  will  be  little 
danger  from  the  attack  of  these  insects.  Sometimes, 
however,  they  appear  in  large  numbers  and  should  be  im- 
mediately killed  by  additional  applications  of  arsenical 
poisons. 

The  three-lined  leaf-beetle  {Lema  trilineata) 

These  leaf-beetles  are  leaf-eating  insects.  Both  the 
adults  and  larvse  of  this  insect  feed  on  potato  leaves.  This 
beetle  is  smaller  and  more  elongated  than  the  Colorado 
potato  beetle  and  has  only  three  black  lines  on  a  yellow 
ground  color.  The  larvae  are  distinguished  by  having  their 
backs  covered  with  their  own  excrement. 

The  adults  hibernate  over  winter  and  come  out  in  the 
spring,  laying  their  eggs  on  the  underside  of  the  potato 
leaves  along  the  veins.  There  are  two  broods  a  year ;  the 
larvse  of  the  first  brood  appear  in  June  and  those  of  the 
second  brood  in  August.  The  adults  of  the  second  brood 
go  into  the  ground  to  hibernate  over  winter. 

Control.  —  This  insect  is  controlled  in  exactly  the  same 
way  as  the  blister  beetles. 

Tortoise-beetles  (Cassida  and  Coptocycla) 

Tortoise-beetles  are  leaf-eating  insects.  The  insects 
of  these  genera  are  of  minor  importance,  but  may  do  some 
damage  in  unsprayed  fields.     Their  oval  shape  and  flaring 


Potato  Insects  and  their  Control  177 

edge  of  the  thorax  give  them  some  resemblance  to  a 
tortoise  shell.  They  are  of  small  size  and  green,  gold  or 
black  in  color. 

The  adults  make  their  appearance  in  May,  having  lived 
through  the  winter  in  crevices  under  bark  and  in  similar 
dry  places  wherever  shelter  could  be  found.  The  female 
begins  to  lay  eggs  soon  after  her  appearance.  The  eggs 
are  laid  singly  on  the  leaf-stems  or  on  the  under  side  along 
the  larger  veins,  and  each  is  covered  with  a  little  daub  of 
black  excrement,  so  that  all  that  is  visible  to  the  eye  is  a 
little  mass  of  black,  pasty  material  that  soon  hardens. 
This  mass  incloses  the  whitish  oval  egg  and  protects  it. 
During  the  first  part  of  June,  many  of  the  eggs  have 
hatched  and  larvse,  eggs  and  adults  may  be  found  on  the 
plants  all  at  once.  "The  larvae  are  decidedly  flattened, 
more  or  less  oval,  with  lateral  spines  or  processes  from  the 
margins,  and  at  the  end  of  the  body  is  a  fork  which,  in 
some  species,  holds  all  the  excrement  voided  during  life 
and  sometimes  the  cast  skins  as  well,  often  making  a  mass 
nearly  as  large  as  the  larvae  itself."  These  feed,  pref- 
erably, on  the  under  surface  of  the  leaves  and  do  much 
damage.  The  larva  pupates  about  the  middle  of  July. 
The  beetles  appear  during  early  August  and  feed  very  little, 
all  trace  being  gone  before  the  beginning  of  September. 
There  is  one  brood  a  year. 

The  potato  jAant-louse  (Macrosiphum  solanifolu) 

This  plant-louse  is  relatively  large  in  size,  and  either  pink 
or  green  in  color.  Its  mouth-parts,  like  those  of  all  plant- 
lice,  are  adapted  for  sucking  the  juices  from  the  tender, 
growing  tips  of  the  vines.  The  infested  vines  grow  brown 
at  the  ends  and  often  die  back  for  four  or  five  inches.     In 


178  The  Potato 

certain  seasons,  these  insects  become  very  numerous  and 
their  depredations  check  the  growth  of  the  vines  con- 
siderably. The  wounds  made  by  the  beaks  of  the  aphids 
often  admit  fungi  and  indirectly  result  in  greater  injury 
than  the  work  of  the  insect  alone. 

The  potato  aphid  passes  the  winter  in  the  egg  stage, 
the  eggs  being  attached  to  weeds.  In  the  early  spring,  the 
adult  insects  are  to  be  found  feeding  on  the  succulent  tips 
of  rose  bushes.  In  July,  the  aphids  migrate  to  potato 
fields  and  start  feeding  there.  The  potato  seems  to  be  an 
ideal  food  for  this  insect,  for  it  increases  in  numbers  very 
rapidly,  a  single  female  often  producing  over  fifty  young 
in  two  weeks.  Late  in  August  or  early  in  September, 
the  lice  leave  the  potato  vines  and  go  to  rose  bushes  or 
other  food  plants.  Here  they  produce  several  more 
generations  of  young.  The  last  generation  of  the  year 
consists  of  wingless  females  and  winged  males.  The 
females  lay  the  over-wintering  eggs  on  the  shepherd's 
purse,  potato,  and  other  food  plants. 

Control.  —  There  are  certain  natural  agencies  of  control 
over  these  insects  which  frequently  make  them  of  little 
consequence.  Among  these  are  cold  weather,  frequent 
rains,  parasitic  fungi  and  insects,  and  various  predacious 
insects.  These  factors  cannot  be  relied  upon,  however, 
to  keep  the  pest  in  check  every  year.  Fall  plowing  will 
turn  under  many  weeds  and  old  leaves  on  which  the  eggs 
have  been  laid.  It  has  also  been  suggested  that  the 
farmer  burn  the  dead  vines  in  the  fall  in  order  to  destroy 
the  eggs.  The  adult  insects  can  be  killed  by  using  any 
good  contact  insecticide  like  one  of  the  tobacco  extracts, 
kerosene  emulsion  and  the  like.  Spraying  is  usually  only 
resorted  to  when  the  insects  become  very  troublesome. 


Potato  Insects  and  their  Control  179 

Leaf-hoppers  (Empoasca  mail) 

These  leaf-sucking  insects  do  some  damage  to  potato 
tops  by  sucking  the  juices  and  making  holes  in  the  leaves. 
The  most  common  of  the  leaf-hoppers  is  Empoasca  rnali, 
which  is  a  small,  elongated,  pale-green  insect,  very  active, 
jumping  and  fl^'ing  readily. 

This  insect  spends  the  winter  either  in  the  adult  or  in 
the  egg  stage.  It  appears  in  the  spring  and  starts  to  feed 
upon  the  apple  or  other  food  plants,  and  soon  lays  its  eggs. 
The  nymphs  from  the  over-wintering  eggs  are  found  about 
the  middle  of  May.  Usually  about  four  broods  develop 
during  the  season.  The  leaf-hoppers  are  generally  all  gone 
by  the  first  of  October. 

Control.  —  They  do  not  require  special  treatment,  never 
appearing  in  sufficient  numbers  to  do  any  great  damage. 
Treatment  for  other  insects  readily  keeps  them  in  check. 

The  potato-stalk  weevil  {Trichobaris  trinotata) 

This  is  a  stalk-boring  insect  which  does  considerable 
damage  in  the  south  central  states.  The  adults  are  small 
ash-gray  beetles  with  a  long  snout,  and  the  larvae  are  small 
white  grubs. 

The  adults  appear  in  the  spring  after  hibernation  and 
eat  holes  in  the  base  of  the  stalk  with  their  long  snouts  and 
deposit  an  egg  in  each  hole.  These  soon  hatch,  and  the 
larvae  make  their  way  into  the  main  stalk  and  branches. 
These  grubs  become  full  grown  near  the  middle  of  August, 
and  then  they  pupate  in  cocoons  which  they  have  spun 
near  the  base  of  the  stalks.  Adults  appear  a  w^eek  later 
and  remain  in  the  stalks  until  the  following  year. 

Control.  —  Since  the  adults  hibernate  in  the  old  stalks, 


180  The  Potato 

the  best  method  to  keep  them  in  check  is  to  rake  the  fields 
over  after  digging  the  potatoes  and  burn  all  the  refuse. 
Destroy  also  all  other  solanaceous  plants  which  may  be 
growing  in  the  neighborhood. 


The  stalk-borer  (Papaipema  nitella) 

The  potato  is  probably  not  the  normal  food  plant  of  this 
insect,  but  when  other  food  material,  such  as  certain  weeds, 
tomatoes,  corn,  cotton  and  some  grasses,  are  lacking,  the 
potato  is  sometimes  infested.  The  adult  is  a  gray  moth, 
and  the  larvae  do  damage  by  boring  into  the  stems  of  the 
plants  on  which  they  feed. 

The  insect  lives  over  winter  by  means  of  eggs  which  are 
laid  in  the  fall  in  masses  of  fifty  or  sixty  on  grasses  and 
weeds.  The  eggs  hatch  in  the  spring,  and  the  larvae 
puncture  the  leaves  and  then  work  down  into  the  stalk. 
Frequently  they  travel  from  one  plant  to  another.  The 
larvae,  when  mature,  eat  holes  in  the  sides  of  the  stalks  and 
pupate.  Late  in  August,  the  adults  emerge  and  lay  eggs 
for  next  year's  flock.     There  is  one  generation  in  a  year. 

Control.  —  The  stalk-borer  should  have  the  same  treat- 
ment as  the  stalk-weevil. 


White  grubs  (Lachnosterna  species)  (Fig.  12) 

These  are  the  larvae  of  the  May-beetles  or  June-bugs. 
They  are  large,  white,  soft-bodied  grubs  which  are  com- 
monly found  in  sod  ground.  They  feed  on  the  roots  of 
many  plants  and  sometimes  eat  into  the  tubers  of  pota- 
toes, especially  those  planted  on  new  ground. 

This  insect  lives  in  the  ground  over  winter  either  as  an 


Potato  Insects  and  their  Control 


181 


adult  beetle  or  as  white  grubs.  It  takes  two  or  three 
years  to  complete  its  life  cycle.  The  adults  lay  eggs  in 
sod  ground  in  June  which  hatch  in  about  two  weeks.  The 
larvae  or  grubs  feed  on  roots  and  require  one  or  two  sum- 
mers to  become  fully  grown. 
They  pass  the  first  winter  as 
grubs  living  deep  down  in  the 
ground  and  the  second  summer 
are  much  larger  and  more 
destructive  than  the  first,  so 
that  those  fields  left  in  sod  one 
year  are  likely  to  be  badly  in- 
fested the  next  year.  The 
larva,  ordinarily,  pupates  in 
June  or  July  of  its  second  year 
and  after  remaining  a  pupa  for  about  three  weeks,  changes 
into  an  adult  beetle  and  remains  in  the  ground  until  the 
next  spring. 

Control.  —  If  the  ground  is  badly  infested  with  white 
grubs  or  wire-worms,  it  should  be  given  a  thorough  fall 
plowing  and  either  plowed  again  or  thoroughly  harrowed 
in  the  spring.  Land  which  has  been  in  sod  for  many  years 
would  ordinarily  need  this  treatment.  Potatoes  should 
not  be  planted  immediately  upon  such  ground,  but  it 
should  be  planted  for  a  year  or  two  to  such  crops  as  buck- 
wheat or  some  of  the  other  small  grains  which  are  damaged 
but  little  bv  white  grubs  or  wire-worms. 


Fig.   12.     White  grub  and 
May-beetle. 


Wire-tcorms  (several  species)  (Fig.  13) 

These  insects  do  much  damage  to  the  roots  of  many  crops, 
including  the  potato.  Like  the  white  grubs,  they  normally 
live  in  sod  ground  and  feed  on  roots,  and  are  not  usually 


182 


The  Potato 


injurious  to  potatoes  unless  the  ground  has  been  in  sod  a 
year  or  two.  Wire-worms  are  the 
long,  hard,  cylindrical  larvse  of  the 
click  beetles.  They  include  several 
species. 

Like  the  June-bugs,  the  eggs  are 
laid  on  sod  ground  and  the  larvae 
require  from  three  to  five  years  to 
mature.  They  transform  to  adults 
under  ground  in  midsummer,  but 
usually  remain  in  the  soil  until  the 
following  spring. 
See  methods  of  control  of  white  grubs. 


Fig.  13.     Wire-worm 
and  the  beetle. 


Control. 


CHAPTER  X 

DISEASES  OF   THE  POTATO 

By  M.  F.  Barrus 

When  healthy  potatoes  are  planted  in  a  warm,  moist  soil, 
vigorous  sprouts  will  grow  up  from  the  tubers.  These 
develop  into  vines  with  green  expanded  leaves.  On 
underground  stems  there  will  be  formed  young  tubers 
which  enlarge  greatly  in  the  latter  period  of  the  growth 
of  the  plant.  When  the  healthy  tuber  is  planted,  the 
food  stored  within  is  used  for  the  production  of  tissue 
for  roots,  stems  and  leaves.  As  soon  as  the  leaves  have 
expanded  they  perform  the  important  task  of  making 
food  during  daylight  from  the  carbon  dioxide  of  the  air 
and  from  water  and  soil  solutions  absorbed  by  the  roots. 
This  food  is  used  for  the  maintenance  and  further  growth 
of  the  plants,  and  whatever  is  made  in  excess  of  this  is 
stored  in  the  tuber  largely  in  the  form  of  starch.  After 
the  vines  have  obtained  their  greatest  growth,  the  leaves 
make  a  large  excess  of  food  above  that  needed  for  main- 
tenance, and  consequently  the  storage  of  food  in  the  tuber 
takes  place  rapidly.  It  is  plainly  to  be  seen,  therefore, 
that  in  order  to  have  a  large  amount  of  food  stored  in 
the  tubers,  that  is,  to  have  a  large  yield,  it  is  necessary 
first  to  have  a  good  growth  of  vines  and  to  have  them 
remain  healthy  until  the  tubers  become  of  maximum  size. 
A  destruction  of  the  leaves  by  any  means  reduces  the 
yield  of  tubers. 

183 


184  TJie  Potato 

Wlien  the  leaves  of  the  plant  become  crinkled  and 
curled,  mottled,  rolled,  spotted,  blighted  or  dead  at  the 
edge,  when  the  vines  show  a  yellowing  and  wilting,  or 
become  stunted,  or  the  stem  shows  discolorations  on  the 
outside  or  within,  or  when  the  tubers  have  rough  scabs 
or  pustules  or  show  rotted  areas,  or  the  tissue  within  is 
streaked  with  brown  or  is  decayed,  we  say  the  plant  is 
diseased.  Any  one  of  these  appearances,  called  symp- 
toms, may  indicate  the  presence  of  disease,  and  its  appear- 
ance means  that  the  plant  is  unable  to  produce  its  maxi- 
mum yield.  It  is  to  the  interest  of  the  farmer  to  know 
what  these  diseases  are  and  especially  to  know  how  to 
prevent  them. 

A  plant,  like  a  person,  may  be  small  and  also  be  healthy. 
Poor  soil  often  produces  small  plants,  and  late  planted 
tubers  may  produce  vines  which  may  be  killed  by  frost 
before  they  have  attained  their  maximum  growth.  Such 
small  plants  are  not  diseased.  Other  things  being  equal, 
however,  small  vines  will  not  produce  as  large  yields  as 
large  vines.  But  plants  may  be  small  because  they  are 
affected  by  some  disease,  so  that  it  is  often  difficult  to 
tell  whether  small  plants  growing  in  a  field  are  affected 
by  disease  or  are  small  for  other  reasons.  Some  plants 
grow  "all  to  vines,"  that  is,  the  vines  continue  to  grow 
vigorously  all  the  season  and  by  so  doing  use  up  a  large 
amount  of  the  food  made  by  the  leaves  so  that  there  is 
but  little  left  for  storage  in  the  tubers.  Such  plants 
usually  have  small  or  unmarketable  tubers.  This  condi- 
tion may  be  brought  about  by  too  much  shade  or  by  a  soil 
too  rich  in  nitrogen.  On  the  other  hand,  such  a  condition 
may  be  the  result  of  a  disease  known,  for  the  want  of  a 
better  name,  as  "large  vines  and  many  small  tubers." 

A  disease  of  a  plant  is  an  abnormal  condition  which 


Diseases  of  the  Potato 


185 


prevents  it  from  completely  carrying  on  its  life  processes 
and  producing  its  fruit  naturally.  There  are  many 
agencies  capable  of  bringing  about  disease  of  the  potato, 
some  of  which  are  not  well  understood  at  present.  Disease 
may  be  brought  about  by  conditions  of  soil  and  climate 
unfavorable  to  the 
plant,  by  physiologi- 
cal disturbances  within 
the  plant,  the  direct 
cause  of  which  is  not 
clear,  and  by  the 
attacks  of  parasitic  or- 
ganisms. Troubles  re- 
sulting from  the  first- 
named  condition  may 
sometimes  be  reme- 
died by  selecting  vari- 
eties or  types  of  plants 
better  adapted  to  the 
climate  in  which  they 
grow,  or  by  adopting 
a  system  of  culture  that  will  overcome  or  obviate  the 
unfavorable  condition.  The  second  group  of  troubles 
are  often  heritable,  and  the  only  means  of  avoiding  them 
are  through  the  elimination  of  tubers  from  affected 
vines  for  planting  purposes.  The  third  type  of  disease, 
and  often  the  most  destructive,  is  caused  by  parasitic 
organisms  and  may  be  communicated  to  healthy  plants 
by  the  transfer  of  the  parasite  or  some  special  portion  of 
its  body  adapted  for  the  purpose. 

For  convenience  in  discussing  them,  we  may  classify 
parasites  of  the  potato  into  plant  and  insect  parasites. 
The  plant  parasites  include  fungi,  bacteria  and    slime- 


FiG.  14.  Section  through  a  part  of  a  dis- 
eased potato  leaf,  showing  the  spore  stalks, 
with  spores  attached,  extending  down 
through  the  breathing  pores  of  the  leaf. 


18G 


The  Potato 


J       ^p^^c 


molds.  A  fungus  is  itself  a  plant,  but  without  leaves  or 
green  color.  It  is  not  able  to  prepare  its  own  food  as 
higher  plants  do,  but  must  live  upon  the  product  of  other 
plants.  jNIany  fungi  and  bacteria  and  most  slime-molds 
are  saprophytes,  that  is,  they  obtain  food  from  the  prod- 
ucts of  plants  or  animals  that  are  dead.  Others  are 
parasites  —  obtaining  their  food  from  the  products  of 
living  plants  by  attacking  the  living  tissues,  injuring  or 
killing  them  and  thus  causing  a  diseased  condition  in  the 
plant  or  the  death  of  the  entire  plant. 

A  fungus  differs  from  a  higher  plant  in  that  it  does  not 
have  roots,  stems  or  leaves  in  the  sense  in  which  we 
generally  regard  these  organs,  but  in  its  vegetative  stage 

it  consists  of  tiny  thread- 
like tubes  or  strands 
known  collectively  as 
mycelia.  The  mycelium 
penetrates  the  food  ma- 
terial and  obtains  its  nu- 
trition from  it.  After  a 
period  of  growth  the 
mycelium  produces  its 
fruiting  body  which  va- 
ries greatly  in  size,  shape 
and  condition  in  the  dif- 
ferent fungi.  The  fruit- 
ing body  bears  the  re- 
productive bodies  known 
as  spores  (Fig.  15),  of  which  enormous  numbers  are 
usually  produced.  These  are  disseminated  by  water,  air 
or  animals,  depending  on  the  kind  of  fungus  producing 
them.  When  spores  of  parasitic  fungi  fall  upon  their 
host  plant,  that  is,  the  plant  from  which  they  are  able 


/^-v 


(After  U.  S.  Dept.  Agr.) 

Fig.  16.  Below  from  right  to  left 
are  shovm  four  stages  in  the  formation 
of  swarm  spores.  The  way  in  which 
the  swarm  spores  germinate  is  shown 
above. 


Diseases  of  the  Potato  187 

to  extract  their  food,  they  will  germinate  under  favorable 
conditions  of  temperature  and  moisture.  Indeed  most 
spores  will  germinate  under  favorable  conditions  without 
the  presence  of  the  host  plant.  These  conditions  vary 
with  different  fungi,  but,  in  general,  a  fairly  warm,  moist 
condition  is  favorable  for  the  germi- 
nation of  most  spores.  The  sprout, 
or  germ-tube  (Fig.  16),  produced  by 
the  germinating  spore  enters  the  tis- 
sue of  the  host  directly  through  the 
wall  which  it  is   able  to  dissolve,    .^^^  ,^^:™;-- 

through     wounds     or     through     the     ing   germ-tube   entering 

breathing  pores.  The  root-hairs  of  ^^  ' 
higher  plants  have  very  tender  walls,  and  these  may  serve 
as  a  point  of  infection  by  parasitic  fungi  of  the  soil.  After 
a  fungus  gains  entrance  to  a  plant,  it  lives  upon  the  cell 
products  and  usually  brings  about  the  death  and  discol- 
oration of  the  tissues  at  the  point,  so  that  the  infested 
area  may  be  seen  as  a  spot,  rot,  blight  or  canker.  The 
fungus,  sooner  or  later,  puts  forth  fruiting  bodies  on  the 
outside  of  its  host,  and  on  these  bodies  the  spores  are 
borne. 

Bacteria  are  plants  of  a  lower  order  than  fungi,  many 
kinds  consisting  of  but  a  single  minute  cell.  In  the 
presence  of  oxygen,  water,  food  and  suitable  temperature 
they  reproduce  very  rapidly.  They  do  not  produce 
spores  like  fungi,  and  are  unable  to  penetrate  unaided 
the  outer  tissues  of  plants,  but  may  enter  the  plant 
through  insect  and  other  wounds  or  through  other  open- 
ings. Thus,  parasitic  bacteria  may  be  carried  from  plant 
to  plant  by  insects  and  be  introduced  into  their  tissues 
during  dry  weather  when  fungi  would  be  unable  to  do 
so.     Bacteria  also  live  entirely  within  the  host  plant  and 


188 


The  Potato 


do  not  produce  fruiting  bodies  on  the  exterior,  though 
the  Hving  bacteria  may  ooze  out  with  the  sap  through 
wounds  or  breathing  pores. 

Most  shme-molds  are  entirely  saprophytic,  though  a 
few  attack  hving  pLants.  The  one  pro(hicing  powdery 
scab  is  the  only  example  of  a  slime-mold  disease  of  the 
potato.  The  slime-mold  differs  from  a  fungus  or  a  bac- 
terium in  that  it  consists  of  a  naked  mass  of  protoplasm, 
often  of  many  cells,  in  its  vegetative  stage.  The  spores 
of  the  one  producing  powdery  scab  germinate  as  a  tiny 
mass  of  naked  protoplasm  which  gains  entrance  to  its 
host  through  the  lenticles  or  breathing  pores  on  the  tuber. 
It  passes  from  cell  to  cell  within  its  host,  infesting  the 
contents  and  itself  greatly  increasing  in  mass.  Finally, 
its  body  is  transformed  into  spores  which  become  exposed 
with  the  rupture  of  the  skin  above  them. 


CLASSIFICATION   OF  CAUSES   OF   DISEASE 

According  to  their  causes,  we  may  classify  the  diseases 
of  potatoes  as  follows : 

Fungous  —  Early  blight,  late  blight,  and  rot, 
Fusarium  dry  rot,  Fusarium 
wilt,  Verticillium  wilt,  rhi- 
zoctoniose,  wart,  and  silver 
scurf. 

Bacterial  —  Common  scab,  black  leg,  soft 
rots,  bacterial  wilt,  streak. 

Slime-mold  —  Powdery  scab. 
Non-        J  Curly  dwarf,  leaf-roll,  mosaic,  spindling  sprout, 
parasitic  |       net  necrosis,  tip-burn,  arsenical  injury. 


Parasitic  • 


Diseases  of  the  Potato  189 

Early  blight  (Plate  X) 

Early  blight,  caused  by  the  fungus  Alternaria  solani, 
appears  as  angular,  dark  brown  dead  spots  on  the  leaves, 
which  may  become  so  numerous  as  to  kill  the  entire  leaf. 
The  spots  are  marked  with  concentric  rings  of  elevation, 
giving  the  dead  area  a  target-board  appearance.  The 
vines  usually  do  not  become  aflFected  until  after  blossom- 
ing has  occurred,  but  may  then  become  so  severe  as  to 
cause  the  vines  to  die.  The  spots  often  occur  around  a 
flea-beetle  puncture  or  other  injury,  but  may  also  be 
found  on  an  otherwise  uninjured  surface.  The  fungus 
commonly  attacks  the  older  and  weaker  leaves  first,  but 
may  spread  from  them  to  the  younger  ones. 

The  disease  may  be  confused  with  tip-burn  or  with 
arsenical  or  other  injury  to  the  foliage.  The  fungus 
may  attack  such  injured  or  dead  area  first  and  later 
spread  to  healthy  tissue.  The  spores  are  large,  thick- 
walled,  many-celled  bodies  produced  on  both  surfaces  of 
the  older  dead  areas.  The  fungus  is  able  to  live  over 
winter  as  a  mycelium  in  the  dead  leaf  tissue,  and  the  spores 
themselves  will  remain  alive  for  more  than  a  year.  They 
germinate  in  water,  each  cell  being  capable  of  sending 
out  a  germ-tube.  These  are  able  to  enter  the  leaf  through 
stomates  or  penetrate  the  epidermis  directly.  The 
fungus  attacks  the  foliage  only,  but  as  a  result  of  the 
attack  the  tubers  may  be  small  and  thus  the  loss  will  be 
considerable.  This  will  depend  upon  the  virulence  of 
the  attack  and  may  amount  to  one-half  or  more  of  the 
crop. 

The  disease  can  be  held  in  check  by  thorough  appli- 
cations of  bordeaux  mixture. 


190  The  Potato 

Late  hUght  (Plate  IX) 

Late  blight,  also  known  as  downy  mildew,  is  caused 
by  the  fungus  Phytophthora  infestans.  It  occurs  in  north- 
eastern United  States  and  adjacent  parts  of  Canada  and 
sporadically  farther  south  and  on  the  Pacific  Coast.  It 
has  also  been  known  for  years  in  many  countries  of  Europe, 
and  has  been  reported  as  occurring  in  Australia  and  in 
the  high  plateaus  of  South  America  where  potatoes  are 
grown.  It  prevails  in  those  regions  where  the  weather  is 
relatively  cool  and  moist,  conditions  most  favorable  for 
the  growth  of  the  potato  itself,  and,  even  there,  is  de- 
structive only  during  especially  favorable  seasons.  For 
this  reason  the  disease  appears  in  epidemic  form  in 
many  sections  in  occasional  periods  of  years,  the  inter- 
vening periods  being  comparati^'ely  free  from  it. 

The  disease  shows  on  the  leaves  as  water-soaked  or 
brown  areas  that  may  occur  on  any  part  of  the  leaf.  In 
moist  weather  these  spots  rapidly  enlarge  so  that  the 
entire  leaf  may  become  affected,  and  over  the  recently 
affected  area,  usually  on  the  lower  surface,  a  fine  white 
mildewy  growth  may  be  noticed.  The  stem  may  be- 
come affected  in  a  similar  manner.  In  moist  weather 
the  affected  areas  soften  instead  of  drying  and  give  off  a 
disagreeable  odor  characteristic  of  decaying  vines. 

The  fungus  causing  the  late  blight  may  attack  the 
tubers  (Plate  IX),  the  upper  surface  of  those  lying  nearest 
the  surface  of  the  soil  being  first  infected,  producing  on 
them  a  discolored,  water-soaked  area  which  may  be  small 
or,  if  the  soil  is  moist,  may  extend  over  much  of  the  tuber. 
The  affected  area  becomes  somewhat  sunken  at  digging 
time  or  later  in  storage  and  the  flesh  has  a  rusty-brown 
color.     This  condition  is  known  as  dry  rot.     The  flesh 


Diseases  of  the  Potato  191 

is  not  affected  to  a  greater  depth  than  one-fourth  to  one- 
half  an  inch,  although  such  affected  tubers  in  a  heavy 
wet  soil  or  even  in  storage  may  be  invaded  by  saprophytic 
fungi  or  bacteria  that  produce  a  soft,  malodorous  condi- 
tion known  as  wet  rot. 

The  fungus  causing  late  blight  lives  as  a  mycelium  in  or 
near  the  margin  of  the  diseased  area  in  affected  tubers. 
Wlien  such  tubers  are  planted  under  conditions  favorable 
to  the  fungus,  namely,  a  warm  moist  soil,  the  mycelium 
will  grow  into  shoots  often  weakening  them  and  some- 
times destroying  them. 

When  these  affected  sprouts  succeed  in  growing,  they 
appear  above  the  ground  as  a  slender,  weak  stalk  often 
hidden  by  healthy  neighboring  ones  from  the  same  tuber. 
On  these  weak  stalks  the  fungus,  during  moist  weather, 
forms  its  fruiting  bodies  on  which  are  produced  a  large 
number  of  spores.  These  are  blown  by  air  currents  to 
neighboring  healthy  vines,  where,  if  the  vines  are  wet, 
they  germinate  in  two  to  four  hours  in  an  interesting 
manner.  An  opening  appears  at  the  tip  of  the  spore, 
and  six  or  more  zoospores  are  pushed  out  as  naked  masses 
of  protoplasm  that  are  able  to  move  about  in  the  water 
on  the  leaf  surface  by  means  of  whip-like  strands  of 
protoplasm  extending  from  their  bodies.  After  moving 
about  for  an  hour  or  so,  they  settle  down  on  to  the  sur- 
face of  the  leaf  and  after  a  time  send  out  a  little  tube,  the 
germ-tube.  The  germ-tube  is  able,  after  a  few  hours,  to 
penetrate  the  surface  of  the  leaf.  Once  inside,  the  germ- 
tube  grows  rapidly  into  a  mycelium  extending  between 
the  cells  and  even  penetrating  them.  These  cells  be- 
come disorganized  and  turn  brown  and  from  them  the 
mycelium  obtains  its  nourishment.  Cell  after  cell  is 
killed  in  this  manner,  and  the  discoloration  resulting  upon 


192  The  Potato 

their  death  is  noticed  as  a  blighting  of  the  leaf.  After 
four  or  more  days,  the  mycelium  has  produced  fruiting 
bodies  bearing  more  spores.  These  are  carried  by  air 
currents  or  by  other  means  to  healthy  leaves,  which  in 
turn  become  infected  if  the  weather  is  wet,  or  they  fall 
to  the  ground,  where  during  rains  they  are  washed  into 
the  soil.  Thus  under  favorable  weather  conditions  the 
fungus  may  spread  from  an  infected  vine  to  neighboring 
ones,  causing  them  to  blight,  and  thence  to  all  the  vines 
in  the  field  until  all  are  blighted.  The  spores,  washed 
into  the  soil,  come  into  contact  with  the  new  tubers  and 
infect  them  in  much  the  same  manner  as  the  leaves  were 
infected,  so  that  they  rot  in  the  manner  described  earlier. 
If  the  soil  remains  wet  and  soggy,  as  heavy  soils  often  do 
during  rainy  periods  of  the  fall,  the  fungus  grows  luxu- 
riantly in  the  tuber  and  produces  fruiting  bodies  on  its 
surface.  Spores  produced  there  infect  other  tubers  in 
the  hill  and  possibly  spread  to  other  hills.  It  has  been 
shown  that  the  fungus  may  fruit  on  the  surface  of  the 
tuber  in  storage  and  infect  mature  tubers  there,  though 
this  does  not  often  happen.  All  that  is  necessary  for 
infection  of  the  tubers  is  the  presence  of  spores  on  their 
surface  under  moist  and  fairly  mild  or  cool  weather. 
Infection  readily  occurs  when  the  blighting  vines  come 
into  contact  with  freshly  dug  tubers.  These  points  are 
of  importance,  as  it  teaches  us  to  leave  blighting  vines 
until  they  are  dead  and  dry  before  digging  unless  we  can 
dispose  of  the  crop  at  once  or  unless  there  is  danger  of 
the  tubers  rotting  badly  in  wet  soil.  Tubers  infected 
shortly  before  digging  time  may  show  no  evidencf  of  it 
then,  but  the  dry  rot  will  appear  later  in  storage. 

It  has  also  been  shown  that  throwing  the  soil  over  the 
tubers  with  a  shovel  plow  to  the  depth  of  four  or  five 


Diseases  of  the  Potato  193 

inches  before  or  at  the  time  the  vines  begin  to  blight  will 
prevent  a  large  amount  of  tuber  infection.  This  method 
of  control  is  a  makeshift  at  best,  and  the  practice  in  some 
localities  is  known  to  have  reduced  the  yield.  Spraying 
the  soil  with  bordeaux  mixture  will  aid  in  preventing 
infection  of  tubers,  but  usually  is  not  practical. 

As  the  fungus  grows  best  in  the  tubers  under  mild  or 
moderately  cool  moist  conditions,  it  naturally  follows  that 
infected  tubers  will  rot  but  little  or  not  at  all  when  stored 
in  a  dry  place  and  held  at  a  low  temperature  (40°  F.  or 
below).  The  application  of  lime  or  formaldehyde  to  the 
tubers  in  storage  is  of  no  value  in  preventing  rot. 

The  disease,  then,  is  caused  by  a  fungus  carried  to  the 
field  with  infected  tubers.  The  fungus  spores  produced 
on  infected  vines  spread  readily  during  moist  weather 
to  the  other  vines  in  the  field  and  to  neighboring  fields, 
producing  blight  whenever  infection  occurs.  Many 
spores  fall  from  the  vines  to  the  soil  below  and  are  washed 
to  the  tubers,  which  upon  infection  sooner  or  later  show 
the  dry  rot.  When  the  soil  remains  wet,  such  tubers 
become  invaded  by  other  soil  fungi  and  bacteria  which 
bring  about  a  soft  malodorous  rot. 

As  a  result  of  many  experiments  it  has  been  found  that 
spraying  the  vines  with  bordeaux  mixture  is  the  best 
practical  way  to  control  the  disease.  Thorough  appli- 
cations made  frequently  during  the  summer  to  keep  the 
new  growth  covered,  especially  before  rainy  periods,  and 
in  the  late  summer  and  the  early  fall,  will  prevent  infec- 
tion of  the  vines.  If  the  vines  do  not  blight,  the  tubers 
will  not  rot.  More  complete  directions  regarding  spray- 
ing practices  will  be  found  under  the  chapter  on  Control 
Measures. 


194  The  Potato 

Rhkoctoniose  (Plates  X  and  XII) 

This  is  a  name  given  to  the  several  symptoms  of  a 
disease  caused  by  the  fungus  Rhizoctonia,  which  when 
producing  its  perfect  spores  is  known  as  Corticum  vagum 
var.  solani.  The  fungus  forms  small  black  irregular 
masses  often  the  size  of  a  half-pea  or  smaller  on  the  sur- 
face of  the  tuber.  These  resemble  httle  chunks  of  muck, 
but  can  be  readily  detected  by  washing  the  tuber,  for 
they  do  not  wash  off  as  soil  does  although  they  can  be 
easily  scraped  off.  These  bodies,  called  sclerotia,  enable 
the  fungus  to  pass  the  winter  without  injury.  In  the 
spring,  when  planted  with  the  tuber  or  even  when  kept 
in  a  moist  place,  a  fine  mycelium  grows  out  from  them. 
This  attacks  the  sprouts  and  produces  cankers  on  them, 
so  that  the  portion  above  is  commonly  destroyed. 
Younger  sprouts  may  then  appear  from  below  the  can- 
kered area,  but  these  in  turn  may  be  infected,  so  that  the 
plants  are  late  in  making  their  appearance  above  the 
ground  or  do  not  appear  at  all.  Affected  plants  that 
succeed  in  appearing  may  continue  to  grow  and  produce 
well.  The  fungus,  however,  commonly  attacks  and 
destroys  the  stolons  and  in  this  way  reduces  the  yield. 
Older  plants  are  sometimes  weakened  by  cankers  on  the 
stems,  and  brown  strands  of  mycelium  may  be  observed 
over  such  affected  areas.  The  cankers  may  be  so  severe 
that  the  vines  become  yellow  in  color  and  the  leaves  roll 
upward  the  same  as  when  the  vine  is  affected  with  black- 
leg. Indeed,  in  such  cases  the  stem  is  sometimes  found 
to  be  decayed  by  a  black-rot  similar  to  black-leg.  Af- 
fected vines  often  have  small  aerial  tubers  formed  in  the 
axils  of  the  leaves  and  the  stems  themselves  are  thick- 
ened.    Such  vines  usually  have  a  large  number  of  small 


■  /"''.S^-.-- 

j';^>>' 

i 

I^'^^^hs^  ^  ^ '  • 

4 

^m^SSty  ^ 

:^k 

^flp' 

^ 

^ 

Plate  X.  —  Potato  diseases.     Top,  part  of  a  potato  leaf  showing  spota 

of  early  blight ;   magnified.     Bottom,  rhizoctoniose. 

(Courtesy  Dept.  of  Plant  Pathology,  College  of  Agriculture,  Cornell  University.) 


Diseases  of  the  Potato  195 

tubers  clustered  close  to  the  base.  The  fungus  produces 
its  spores  during  moist  weather  on  a  thin,  white,  frost-like 
growth  extending  over  the  base  of  the  stalks. 

This  fungus  is  able  to  attack  many  kinds  of  plants  and 
to  live  as  a  saprophyte  in  the  soil  from  year  to  year.  For 
this  reason  it  is  difficult,  if  not  impossible,  to  eradicate  it. 

The  sclerotia  on  the  tubers  can  be  killed  by  soaking 
the  tubers  in  corrosive  sublimate  solution,  and  if  this 
treatment  is  coupled  with  a  judicious  rotation  of  crops 
on  the  land,  the  injury  from  the  disease  will  be  greatly 
reduced. 

Fusarium  wilt 

This  disease  is  caused  by  the  fungus  Fusarium  oxy- 
sporum,  which  gains  entrance  through  the  roots  from  in- 
fected tubers  or  from  the  soil  and  works  upward  in  sap 
vessels,  interfering  in  that  way  with  the  normal  circulation 
of  the  sap.  The  fungus  mycelium  destroys  the  roots  and, 
later,  fruits  on  them,  producing  abundant  spores.  The 
diseased  condition  of  its  roots  and  of  the  sap  vessel  causes 
a  yellowing,  dwarfing  and  finalh-  a  wilting  and  dying  of 
the  vines.  The  stem  pulls  up  easily  and  its  tissues  beneath 
the  outer  layer  have  a  light  brownish  color.  This  color 
in  the  vascular  tissues  extends  to  the  roots,  stolon,  and 
tubers.  A  section  across  an  affected  tuber  near  the  stem 
end  shows  a  brown  ring  of  sap  vessels.  This  browning  of 
the  vascular  ring  is  associated  with  some  other  diseases 
and  is  always  found  in  tubers  in  which  this  Fusarium  has 
developed  to  any  extent,  although  in  the  earlier  stages  of 
infection  no  discoloration  may  be  noticed. 

Such  diseased  tubers  should  never  be  used  for  seed 
purposes,  as  vines  coming  from  them  nearly  always  be- 
come infected.     The  only  successful  way  to  control  the 


196  The  Potato 

disease  is  the  selection  of  tubers  from  healthy  plants  and 
a  wide  rotation  of  crops  as  outlined  under  the  chapter  on 
Control  Measures. 

Vertidllium  wilt 

This  wilt  is  caused  by  the  fungus  Verticillium  albo-atrum 
and  shows  symptoms  much  like  the  Fusarium  wilt,  and 
the  two  are  very  easily  confused  in  the  field.  The  fungus 
Verticillium  gains  entrance  to  the  plant  in  much  the  same 
way  and  also  inhabits  the  sap  vessels  of  the  plant.  Af- 
fected plants  show  yellowing,  wilting  and  dying  of  the 
leaves,  beginning  with  the  lower  ones  and  progressing 
rapidly  upward.  The  plants  have  a  straggling  appear- 
ance, usually  die  earlier  than  is  normal  and  yield  poorly. 
As  with  Fusarium  wilt  the  tissues  underlying  the  outer 
layers  of  cells  show  a  brown  discoloration,  which  in  this 
case  extends  upwards  into  the  branches  as  well  as  down- 
ward into  the  roots,  stolons  and  tubers.  The  tubers 
show  a  blackened  ring  in  a  section  of  the  stem  end.  The 
fungus  passes  the  winter  in  such  infected  areas  of  the 
tuber  and  is  also  capable  of  living  in  the  soil.  The  same 
methods  of  control  should  be  practiced  as  for  Fusarium 
wilt. 

Fusarium  dry  rot  (Plate  XI) 

This  rot,  caused  by  one  or  more  species  of  Fusaria,  is 
a  dry  rot  extending  deep  into  the  tuber.  The  surface 
of  the  rotted  area  is  much  wrinkled  and  often  shows 
numerous  clusters  of  a  white,  moldy  growth.  The  fun- 
gus gains  entrance  to  the  tuber  through  the  skin  wounds 
or  through  lesions  caused  by  other  fungi,  so  that  the  rot 
may  occur  at  any  point  on  the  tuber.  The  powdery 
dry  rot  caused  by  Fusarium  trichothecioides,  common  in 


Diseases  of  the  Potato  197 

the  western  United  States,  "spreads  rapidly  in  potatoes 
in  transit  to  market  or  stored  under  unfavorable  condi- 
tions." None  of  these  dry  rots  is  known  to  affect  the  vine 
to  any  extent.  The  fungi  causing  them  will  live  in  the 
soil  and  infect  the  new  crop  when  an  opportunity  comes, 
so  that  in  control  all  rotted  tubers  should  be  discarded 
for  planting. 

Silver  scurf 

This  is  caused  by  the  fungus  Spondylocladium  atro- 
virens,  recently  introduced  from  Europe,  and  has  been 
commonly  observed  in  the  United  States.  It  shows  as 
dark  spots  or  areas  on  the  surface  of  the  tuber.  In  these 
areas  fine  black  points  are  found  which  make  up  the  spore- 
bearing  area.  The  fungus  destroys  the  skin  so  that  the 
moisture  escapes  and  the  affected  tuber  shrinks  badly. 
The  affected  areas  at  this  time  and  even  before  have  a 
silvery  luster,  a  character  which  gives  the  disease  its 
name.  The  market  value  of  such  tubers  is  lessened,  and 
they  should  not  be  used  for  planting,  as  seed  treatment 
is  apparently  ineffective  in  destroying  the  fungus. 

Potato  ivart 

This  disease,  caused  by  one  of  the  lower  forms  of 
fungi  called  Synchitrium  endobioticum,  does  not  appear  in 
the  United  States  and  should  continue  to  be  kept  out  by 
strict  quarantine  measures.  The  disease  has  been  known 
in  Hungary  since  189G.  It  has  been  found  in  many 
European  countries  and  also  in  Newfoundland.  It  is 
reported  to  be  very  destructive  and  is  very  difficult  to 
control,  a  long  rotation  of  crops  being  the  only  measure 
recommended. 


198  The  Potato 

The  fungus  causing  the  disease  gains  entrance  into  the 
eyes,  which  become  black  and  swollen.  "In  more  ad- 
vanced stages  one  or  more  nodules,  varying  in  size  from 
that  of  a  wrinkled  pea  to  a  lump  as  large  or  larger  than 
the  tuber  itself,  may  be  found.  These  are  green  where 
they  project  from  the  ground  and  white  below,  turning 
as  they  grow  old  to  dark  brown  or  almost  black.  They 
have  a  wrinkled  coral-like  appearance  like  the  head  of  a 
cauliflower.  'A  still  more  advanced  stage  occurs  when 
the  fungus  has  utilized  every  particle  of  food  stored  in 
the  tuber  and  has  reduced  it  to  a  brownish  black  soft 
mass,  giving  off  a  very  unpleasant  putrefactive  odor.' 
Such  potatoes  cannot  be  harvested  whole.  The  black 
pulpy  mass  breaks  up,  liberating  millions  of  sporangia 
(spore-sacs)  which  live  for  years  in  the  soil.  These 
sporangia  have  been  known  to  infect  potato  crops  after 
an  eight-year  interval."  ^ 

Common  scab 

Common  scab,  caused  by  a  soil  bacterium,  Actinomyces 
chromogenus,  is  too  well  known  to  require  detailed  de- 
scriptions. The  organism  affects  only  the  outer  layers  of 
cells,  though  there  are  deep  scabs  supposed  by  some  to 
be  caused  by  the  same  organism.  It  has  been  shown 
that  gnats  and  possibly  other  insects  may  be  responsil)le 
for  the  original  deeper  injury,  though  the  scab  may  also 
be  present. 

The  scab  organism  winters  over  on  the  scabby  tuber,  but 
may  also  live  from  year  to  year  in  the  soil.  Badly  scabbed 
tubers  should  not  be  planted.  Clean  tubers,  as  well  as 
those  not  badly  scabbed,  after  being  treated  may  be 

»  U.  S.  D.  A..  Farmers'  Bui.  489. 


Plate  XII.  —  Spindling  potato   sprouts ;    upper  picture,   the   disease 

rhizoctiniose. 

(Courtesy  Dept.  of  Plant  Pathology,  College  of  Agriculture,  Cornell  University.) 


Diseases  of  the  Potato  199 

planted  on  land  where  crops  have  been  rotated.  Lime, 
wood  ashes,  manure  and  other  materials  giving  alkaline 
reaction  should  not  ordinarily  be  used  on  potato  soil  in 
connection  with  the  growing  of  that  crop.  If  it  is  neces- 
sary to  apply  any  of  these  substances  in  order  to  grow 
other  crops  the  application  should  be  made  in  the  fall 
after  digging  the  potatoes.  Manure  may  be  applied  best 
as  a  top  dressing  to  the  meadow. 

Black-leg 

This  disease,  which  is  caused  by  the  bacterium  Bacillus 
phytophoni^,  affects  the  vines  and  tubers.  Infected 
vines  have  a  lighter  green  color  than  is  usual  and  have  a 
stiff  upright  growth  instead  of  the  normal  spread  of  foli- 
age. The  leaflets  have  a  tendency  to  roll  about  the  mid- 
rib. The  plant  also  may  be  smaller  than  it  would  natu- 
rally be,  though  this  is  not  always  so.  The  base  of  the 
stem  is  quite  black  and  somewhat  shriveled.  The 
diseased  area  commonly  extends  two  or  three  inches 
above  the  ground,  sometimes  much  farther.  It  also 
extends  downward  to  the  old  seed  tuber  and  may  extend 
into  the  stolons  and  young  tubers. 

The  affected  tubers  may  show  a  stem-end  black-rot, 
and  when  cut  lengthwise  sometimes  show  a  black,  foul- 
smelling  center  decay  and  even  a  hollowed  condition. 
This  center  decay  may  be  present  with  little  evidence  of 
it  at  the  surface. 

The  disease  is  distributed  mainly-  by  affected  seed 
tubers,  or  by  bruised,  cracked  or  decayed  tubers  harbor- 
ing the  organism.  Control  consists  in  the  selection  of 
seed  tubers  from  healthy  plants,  in  discarding  bruised, 
cracked  and  rotted  tubers,  and  in  seed  treatment. 


200  The  Potato 


Bacterial  wilt 

Bacterial  wilt,  caused  by  the  bacterium  Bacillus 
solanacearum,  is  a  disease  that  affects  potatoes,  tomatoes, 
eggplants  and  a  few  other  solanaceous  plants.  It  occurs 
mostly  in  the  southern  United  States.  The  vines  wilt  sud- 
denly, often  on  a  single  stalk,  but  later  affecting  the  entire 
plant.  The  stems  lose  their  bright  green  color  and  be- 
come shriveled  and  blackened.  The  vascular  tissues,  at 
an  early  stage,  have  a  brown  color  somewhat  similar  to 
that  described  for  Fusarium  wilt.  This  color  can  be 
seen  through  the  outer  cells  and  extends  upward  as  nar- 
row black  streaks,  even  out  upon  the  leaf  petioles  and 
vines.  When  such  stems  are  cut  across,  tiny  drops  of 
liquid  ooze  out  of  the  vessels  at  the  cut  surface.  These 
are  of  a  dirty  or  yellowish  white  color,  but  not  sticky  or 
foul  smelling.  Examination  with  a  microscope  shows 
them  to  be  swarming  with  bacteria. 

This  discoloration  of  the  stem  extends  downward  into 
the  stolons  and  tubers.  A  section  across  an  infected 
tuber  at  the  stem  end  usually  shows  a  blackening  of 
vessels,  making  a  dark  ring  around  the  cut  surface  of  the 
tuber  near  the  periphery.  Bacteria  similar  to  those 
found  in  the  stem  are  present  in  these  vessels  of  the  tuber 
and  later  invade  the  other  tissues,  finally  rotting  the 
entire  inside  of  the  tuber. 

The  bacillus  is  carried  from  infected  to  healthy  plants 
by  insects  that  infest  the  potato  vines.  Probably  this 
is  the  common  means  of  dissemination.  Control,  there- 
fore, would  consist  in  destroying  the  insects  as  far  as 
possible  and  in  the  early  removal  of  infected  plants  from 
the  field. 


Diseases  of  the  Potato  201 

Powdery  scab   (Plate  XI) 

Powdery  scab  is  a  disease  of  the  tuber  which  is  caused 
by  a  sHme-mold,  Spongospora  suhterranea.  It  may  be 
easily  observed  at  an  early  stage  in  young  tubers  as 
brownish  colored  blisters.  These,  later,  show  as  pits 
filled  with  a  brown  powder,  the  spores  of  the  parasite. 
These  pits  are  bordered  by  the  torn  skin  of  the  tuber. 
In  storage  the  slime-mold  may  continue  to  be  active, 
causing  a  dry  sunken  rot  about  the  pit.  A  cankerous 
stage  of  the  disease  has  been  described  as  occurring  in 
low,  wet  lands,  in  which  case  the  deeper  tissues  of  the 
tuber  are  invaded  by  the  slime-mold  and  by  other  organ- 
isms, so  that  it  becomes  badly  rotted.  The  disease  has 
not  been  serious  in  the  United  States,  and  its  develop- 
ment seems  to  be  arrested  in  the  warmer  potato  sections. 

The  parasite  is  disseminated  by  the  distribution  of 
affected  tubers  and  by  any  agent  upon  which  the  spores 
may  become  lodged.  The  disease  is  difficult  to  control, 
but  it  is  said  to  be  materially  reduced  by  seed  treatment 
and  rotation  of  crops.  Affected  tubers  should  be  de- 
stroj^ed  by  burning  or  by  boiling,  and  no  tubers,  even 
though  healthy,  coming  from  fields  known  to  be  infested 
should  be  used  for  planting. 

Tip-hum 

This  is  a  disease  characterized  by  a  browning  and 
shriveling  of  the  tips  and  margins  of  the  leaves.  The 
trouble  may  become  quite  severe  and  greatly  reduce 
the  yield  of  tubers.  It  is  often  confused  with  blight,  but 
it  is  not  due  to  parasites,  but  to  hot,  dry  weather  follow- 
ing a  period  when  the  conditions  of  temperature  and 


202  The  Potato 

moisture  favored  a  rapid  growth  of  the  vines.  Cultural 
practices  that  aid  in  the  conservation  of  moisture  com- 
bined with  frequent  applications  of  bordeaux  mixture 
will  reduce  the  amount  of  leaf-area  injured. 

Arsenical  injury 

This  is  a  burning  caused  by  a  heavy  application  of 
paris  green  or  other  insecticides  containing  free  arsenious 
acid.  The  injury  often  resembles  early  blight,  but  is 
lighter  colored  and  usually  occurs  about  flea-beetle  punc- 
tures or  other  injuries  to  the  leaf,  while  early  blight  spots 
may  occur  on  the  otherwise  uninjured  leaf.  The  neces- 
sary amount  of  the  more  caustic  poisons  used  with  bor- 
deaux mixture  or  with  equal  parts  of  lime  should  cause  no 
burning. 

Spindling  sprout  (Plate  XII) 

Spindling  sprout  is  a  disease  characterized  by  very 
small,  weak,  needle-like  sprouts  coming  from  the  eyes 
instead  of  large  vigorous  ones.  Vines  from  such  sprouts 
remain  small  and  weak  and  only  small  unmarketable 
tubers  are  produced  from  such  hills.  It  is  believed  that 
tubers  becoming  unduly  heated  by  the  hot  soil  during 
their  growth  produce  sprouts  of  this  character.  If  this 
is  true,  northern-grown  seed  is  less  likely  to  be  affected. 

Net  necrosis 

This  name  is  applied  to  a  diseased  condition  of  tubers  in 
which  brown  streaks  occur  within  the  tuber.  These 
streaks  are  confined  largely  to  the  vascular  system,  though 
they  do  not  appear  as  a  dark  ring  on  the  surface  of  a  cut 
across  the  tuber  as  is  usually  the  case  with  other  vascular 


Diseases  of  the  Potato  203 

diseases,  but  they  may  also  be  found  within  the  central 
area  of  the  cut  surface.  They  may  be  found  throughout 
the  length  of  the  tuber  or  be  confined  to  the  stem  end. 
The  exterior  appearance  of  the  tuber  gives  but  little 
indication  of  conditions  within.  The  vines  also  become 
affected,  but  the  symptoms  have  not  been  studied  care- 
fully enough  to  differentiate  them  from  those  of  wilt 
disease.  No  organism  has  been  found  associated  with 
the  streaks  in  the  tubers,  but  an  organism  has  been  found 
associated  with  affected  stems  and  roots.  Affected  tubers 
should  be  discarded  for  planting  as  they  may  produce 
weak  plants,  but  they  are  not  unfit  for  food.  The  same 
or  a  similar  disease  is  known  in  England  as  "Sprain" 
and  in  Germany  as  "  Eisenfleckigkeit." 

Curly  dwarf 

Curly  dwarf  is  a  non-parasitic  disease  characterized 
by  a  wrinkling  and  curling  of  the  leaf-blade  about  the 
veins  and  midribs.  Affected  plants  are  usually  dwarfed 
and  die  earlier  than  healthy  ones,  though  all  stages  of  the 
disease  may  exist  in  a  field,  and  in  some  plants  it  may  be 
so  slight  as  to  be  hardly  noticed.  The  yield  in  advanced 
cases  is  very  much  reduced.  Tubers  from  affected 
plants,  while  they  show  no  evidence  of  disease  when 
planted,  will  produce  vines  that  show  a  more  advanced 
stage  of  the  disease.  Since  the  presence  of  the  disease 
is  partly  responsible  for  reduced  yields,  no  tubers  from 
affected  vines  should  be  planted.  The  elimination  of 
these  can  best  be  accomplished  by  inspection  of  the 
vines  in  the  field  about  blossoming  time  of  the  plant,  at 
which  time  affected  hills  should  be  removed  or  marked 
for  removal. 


204  The  Potato 


Mosaic 


This  disease  is  characterized  by  a  crinkhng  of  the 
fohage  and  by  a  mottled  condition  due  to  numerous  small 
areas  of  the  leaf-blade  having  a  lighter  green  color  than 
is  usual.  In  some  plants  this  is  not  especially  notice- 
able, for  there  are  all  gradations  from  healthy  plants  to 
badly  diseased  ones.  The  disease  is  more  commonly 
found  on  white  sprout  varieties  and  is  said  to  reduce  the 
yield  materially.  Since,  like  curly  dwarf,  it  is  transmitted 
by  means  of  the  tuber,  the  same  selection  should  be  prac- 
ticed. 

Leaf-roll 

Leaf-roll  is  the  name  given  to  a  non-parasitic  disease 
of  the  plant  and  is  characterized  by  a  dwarfing  and  a 
yellowing  of  the  vines  and  by  an  upward  rolling  of  the 
leaflets  about  their  midrib.  The  leaves  have  a  tendency 
to  point  upward  and  are  rather  stiff  to  the  touch.  There 
are,  perhaps,  several  types  of  the  disease.  In  one  type 
the  lower  leaves  at  first  show  a  tendency  to  roll  and  be 
stiff  though  the  plant  is  otherwise  normal  in  appearance. 
In  another  type  the  foliage  has  a  yellowish  cast.  The 
leaflets  of  the  upper  and  younger  leaves  point  upward 
and  roll  and  often  show  a  rose  or  light  purple  color  at  the 
lower  margins.  There  are  all  gradations  of  the  disease, 
and  the  well-marked  t^-pes  show  great  reduction  of  growth 
and  yield.  The  disease  is  transmitted  by  means  of  the 
tubers,  so  that  rigid  selection  in  the  field  is  necessary  to 
avoid  it. 

The  cause  of  curly-dwarf,  mosaic  and  leaf-roll  is  un- 
known. Many  theories  have  been  advanced  to  explain 
them,  but  it  is  unnecessary  to  discuss  them  here.     All 


Diseases  of  the  Potato  205 

three  diseases  are  evidently  widespread  and  may  be 
important  factors  in  causing  reduced  yields  and  "running 
out"  of  potatoes.  Tubers  from  such  vines  are  usually 
small.  For  this  reason  the  selection  of  small  tubers  from 
the  bin  is  likely  to  increase  the  percentage  of  such  affected 
plants.  It  is  possible  to  avoid  them  by  the  selection  out- 
lined in  the  chapter  on  Control  Measures. 

Constitutio7ial    degeneracy  and   other  weakened   conditions 
of  plants 

Constitutional  degeneracy  is  a  name  given  to  a  condi- 
tion of  weakness  of  growth  showing  as  small,  often  spin- 
dling stems  producing  but  a  few  small  tubers  to  a  hill. 
Such  a  condition  is  inherent  in  the  plant  and  is  inherited 
by  the  progeny.  This  trouble  may  be  confused  with 
similar  conditions  associated  with  the  non-parasitic 
diseases  already  enumerated.  Very  small,  spindling 
plants  producing  no  commercial  tubers  are  often  found 
to  be  associated  with  an  early  rotting  of  the  seed  tuber 
after  being  planted,  and  similar  plants  sometimes  appear 
when  the  only  eye  on  the  piece  of  tuber  is  near  the  cut 
surface.  Rotting  of  tubers  may  be  due  to  such  prac- 
tices as  keeping  cut  tubers  undusted  a  week  or  more 
before  planting  and  as  planting  cut  tubers  in  hot  soil  or 
leaving  them  exposed  to  the  sun  after  hand-planting. 
Avoiding  such  practices  may  be  of  assistance  in  reducing 
the  number  of  weak  plants  in  the  field,  but  tubers  from 
degenerate  hills  should  never  be  used  for  seed.  The 
elimination  of  these  can  be  accomplished  to  some  extent 
by  grading,  but  selection  from  the  field  is  the  surest  way. 


CHAPTER   XI 

CONTROL  MEASURES  AGAINST  DISEASES 

By  M.  F.  Barrus 

It  will  be  noticed  from  reading  the  preceding  pages 
that  for  some  diseases  the  selection  of  seed  tubers  is 
advised  and  for  others  seed  treatment,  crop  rotation  or 
spraying  is  recommended.  It  may  be  necessary  to  prac- 
tice more  than  one  control  measure  in  order  to  control 
some  diseases.  P'or  the  seed  potato  grower,  it  is  desirable 
and  is  becoming  more  and  more  necessary  that  all  meas- 
ures be  employed  that  will  tend  to  produce  sound  tubers 
free  from  all  diseases.  Detailed  directions  for  carrying 
out  these  measures  are  given  in  these  pages. 

Control  of  curly-divarf ,  mosaic  and  leaf-roll 

As  has  already  been  pointed  out,  such  diseases  as  curly- 
dwarf,  mosaic  and  leaf-roll,  transmitted  by  the  tubers, 
cannot  be  detected  by  the  appearance  of  the  tuber  out- 
side or  within.  There  is  very  little  or  no  outward  evi- 
dence on  tubers  affected  with  Fusarium  and  ^^erticillil^n 
wilt,  bacterial  wilt  and  net  necrosis,  and  occasionally  on 
some  tubers  affected  with  black-leg.  Even  a  section  of 
the  stem  end  will  sometimes  fail  to  reveal  the  presence 
of  these  last-named  diseases.  In  such  cases,  it  is  very 
206 


Control  Measures  207 

necessary,  if  these  diseases  are  to  be  avoided,  to  inspect 
the  field  one  or  more  times  during  the  growing  season  in 
order  to  detect  the  affected  hills  from  the  appearance  of 
the  vines.  If  only  one  inspection  can  be  given,  this  should 
be  made  at  about  the  blossoming  time,  because  the  non- 
parasitic and  other  troubles  can  be  best  detected  at  this 
time.  A  second  inspection  before  the  vines  die  will  often 
reveal  diseased  vines  that  could  not  be  seen  earlier.  At 
the  time  of  inspection  all  diseased  hills  should  be  marked 
for  removal  before  digging  the  others  in  order  that  they 
may  not  be  mixed  with  them.  If  there  is  a  considerably 
large  percentage  of  them,  more  than  10  or  15  per  cent, 
the  crop  should  not  be  used  for  commercial  seed  purposes. 
The  grower,  however,  may  select  from  such  a  field  plants 
that  are  healthy  for  his  own  seed,  and  these  should  be  dug 
before  the  others  and  stored  by  themselves. 

Field  inspection 

The  grower  may  feel  that  he  is  unqualified  to  do  such 
inspection  himself,  but  certainly  he  can  detect  poor  hills, 
and  with  a  little  instruction  from  an  expert  can  learn  to 
distinguish  the  various  diseases.  If,  however,  individual 
farmers  growing  seed  potatoes  for  sale  make  their  own 
inspections,  there  will  be  a  great  diversity  of  standards, 
hence  it  is  more  practical  for  one  man  to  inspect  all  the 
fields  in  a  certain  locality.  Such  a  man  should  be  trained 
for  the  work.  He  may  be  employed  by  an  association  of 
potato-growers  or  by  some  other  organization,  or  he  may 
be  an  official  inspector  of  the  state  or  country  employed 
to  inspect  fields,  and  tubers  after  digging,  for  the  purpose 
of  certifying  them.  Some  such  method  will  greatly  im- 
prove the  seed  stock,  and  the  grower  of  such  stock  will 


208  The  Potato 

not  only  be  able  to  secure  better  prices,  but  will  increase 
his  own  yields  because  of  the  use  of  better  seed.  The 
time  will  not  be  long  before  the  southern  potato-grower 
will  demand  seed  tubers  certified  by  some  responsible 
organization,  and  poor  seed  will  find  a  market  for  table 
stock  or  some  other  purpose. 

Not  all  the  vines  thought  to  be  healthy  in  the  field  will 
produce  satisfactory  seed  tubers.  There  may  be  hills 
among  them  that  produce  a  small  number  of  marketable 
tubers,  and  these  should  be  eliminated  from  seed  stock,  if 
possible.  However,  this  can  be  done  only  by  digging 
each  hill  separately  and  selecting  tubers  from  desirable 
hills,  as  explained  in  an  earlier  chapter.  Growers  should 
do  this  whenever  possible  to  improve  their  own  seed,  but, 
to  improve  further  the  seed  stock  for  sale,  much  can  be 
done  by  grading  because  of  the  small  tubers,  many  of  which 
come  from  weak  or  diseased  hills.  Growers  at  planting 
time  should  discard  all  rotted,  bruised  or  badly  scabbed 
tubers,  for  these  are  not  as  satisfactory  as  healthy,  smooth 
ones,  even  when  treated. 

Seed  treatment  to  prevent  disease 

Seed  treatment  as  directed  will  destroy  organisms  living 
on  or  anchored  on  the  surface  of  the  tuber.  For  this 
reason,  it  is  to  be  advised  when  such  diseases  as  com- 
mon scab,  powdery  scab,  rhizoctoniose  and  black-leg  are 
troublesome.  Treated  tubers  often  give  a  better  stand 
because  rot  organisms,  ordinarily  saprophytic,  found  on 
the  surface  of  the  tuber  are  destroyed.  Treating  the 
seed  also  eliminates  the  danger  of  introducing  disease 
organisms  into  new  soil  or  soil  that  has  been  freed  from 
them  to  a  greater  or  less  extent.      Few  growers  have 


Control  Measures  209 

believed  that  these  organisms  introduced  with  the  seed 
affect  not  only  the  crop  of  that  year  but  remain  in  the 
soil  to  attack  subsequent  crops  of  the  same  or  other  kinds. 

Treating  seed  tubers  is  not  as  troublesome  as  some 
farmers  think.  The  treatment,  if  desired,  can  be  made 
several  weeks  in  advance  of  planting,  but  less  handling  is 
necessary  if  it  is  made  immediately  before  cutting.  Where 
one  has  only  one  hundred  bushels  or  less  to  be  treated,  it 
is  convenient  to  place  two  or  more  barrels  on  a  platform, 
which  should  be  high  enough  to  draw  the  solution  off 
through  a  hole  near  the  bottom  of  the  barrel.  The  pota- 
toes are  dumped  into  the  barrels  and  are  covered  with 
the  solution,  which  may  have  been  prepared  in  another 
barrel.  One  barrel  of  solution  will  cover  two  barrels  of 
potatoes.  After  they  have  soaked  the  required  length  of 
time,  the  solution  may  be  drawn  off  at  the  bottom  and 
emptied  into  the  barrel  in  which  it  was  prepared.  The 
treated  tubers  can  now  be  emptied  on  to  the  ground  to  be 
dried,  but  care  should  be  taken  that  they  are  not  over- 
heated by  the  sun.  The  barrels  can  be  filled  again  with 
potatoes  and  the  same  solution  used  once  more.  While 
waiting  for  this  lot  to  soak  the  tubers  already  treated 
may  be  cut  for  planting.  This  saves  time.  By  using 
two  barrels,  it  is  possible  for  one  man  to  treat  about  50 
bushels  of  potatoes  in  a  day  and  have  time  to  cut  tubers 
for  planting  between  treatments.  Two  men  can  treat 
about  250  bushels  in  one  day  by  the  use  of  10  barrels 
in  making  the  treatment. 

Either  formaldehyde  or  corrosive  sublimate  may  be 
used.  The  former  is  much  cheaper,  less  poisonous  and 
can  be  used  in  metal  vessels  if  desired,  but  it  is  not  as 
effective  in  destroying  the  sclerotia  of  Rhizoctonia  as  cor- 
rosive sublimate.     A  pint  or  pound  of  40  per  cent  form- 


210  TJie  Potato 

aldehyde,  costing  about  30  cents,  should  be  diluted  with 
30  gallons  of  water.  This  can  be  used  over  and  over 
again  for  at  least  ten  times  without  losing  strength,  but 
the  quantity  will,  of  course,  be  diminished  with  each  treat- 
ment. The  tubers  should  be  soaked  in  it  for  two  hours. 
A  longer  time  may  injure  the  sprouting  power  of  the  tuber. 
When  corrosive  sublimate  is  used,  four  ounces  of  the  dry 
powder,  costing  about  50  cents,  should  be  used  to  30 
gallons  of  water.  The  powder  should  first  be  dissolved 
in  a  quart  or  two  of  warm  water  and  then  added  to  the 
other.  It  dissolves  more  slowly  in  cold  water.  The  solu- 
tion should  not  come  in  contact  with  metal,  as  it  reacts 
with  it  and  loses  strength.  Neither  should  it  be  used 
more  than  three  times  in  treating  potatoes  unless  renewed 
with  fresh  solution,  for  it  loses  its  strength  rapidly  with 
use.  Tubers  should  be  soaked  in  it  for  at  least  one  and 
one-half  hours,  but  never  longer  than  five  hours.  Great 
care  should  be  taken  in  its  use,  for  it  is  exceedingly  poison- 
ous.    Treated  tubers  should  never  be  used  as  food. 

Where  one  has  large  quantities  of  tubers  to  be  disin- 
fected at  one  time,  the  formaldehyde  gas  treatment  may 
be  used.  For  this  purpose  the  tubers  should  be  placed  in 
crates  or  in  shallow  slatted  bins  so  as  to  permit  the  free 
movement  of  gas  about  them.  The  disinfecting  room 
should  be  made  as  air-tight  as  possible.  Spread  potas- 
sium permanganate  evenly  over  the  bottom  of  a  large 
deep  pan  or  bucket.  Twenty-three  ounces  should  be 
used  for  each  1000  cubic  feet  of  space  within  the  room. 
Pour  over  the  permanganate  three  pints  of  40  per  cent 
formaldehyde  for  each  1000  feet  of  space.  Give  the  pan 
a  tilt,  leave  the  room  as  quickly  as  possible,  and  close  the 
door  tightly,  leaving  it  closed  for  24  hours  or,  at  least,  over 
night.     The  door  can  then  be  opened  and  the  room  aired 


Control  Measures  211 

out,  after  which  the  potatoes  may  be  handled  as  any 
other  treated  tubers.  The  following  recommendations 
should  be  observed  by  those  using  this  method.  Make 
the  treatment  before  the  potatoes  sprout.  Place  the 
generating  pan  so  that  no  potatoes  are  within  three  feet 
of  it  and  none  directly  above  it.  Use  at  least  167  bushels 
of  potatoes  for  each  1000  cubic  feet  of  space  or  injury 
will  result  to  the  tubers.  This  injury  shows  as  a  pitting 
about  the  lenticels.  Do  not  attempt  treatment  when  the 
temperature  of  the  room  is  below  50°  F.  It  is  most 
affective  at  80°  F.  Thoroughly  wet  the  floor  of  the  dis- 
infecting room  with  boiling  water  just  before  adding  the 
formaldehyde  to  the  permanganate,  as  moisture  in  the  air 
of  the  room  is  very  essential  for  effective  work.  Do  not 
attempt  to  treat  potatoes  in  sacks  or  piled  high  in  bins. 

The  question  often  arises  as  to  whether  the  crates  or 
bags  in  which  the  tubers  are  to  be  carried  to  the  field 
should  be  sterilized  or  whether  cutting-knives  should  be 
often  disinfected.  It  is  possible  for  spores  of  the  organ- 
isms causing  potato  diseases  to  be  carried  on  containers 
or  implements  and  later  come  in  contact  with  the  tuber 
under  such  conditions  that  infection  may  take  place. 
The  writer  is  of  the  opinion  that  infection  in  this  manner 
does  not  frequently  take  place,  but  if  one  desires  to  avoid 
every  possible  contamination,  this  disinfection  will  be 
necessary.  It  may  even  be  desirable  when  such  diseases 
have  been  very  troublesome,  but  ordinarily  it  is  not  neces- 
sary, although  one  should  use  judgment  in  the  matter. 

If  potatoes  are  cut  more  than  a  few  days  in  advance  of 
planting,  they  should  be  dusted  to  prevent  decay  from 
the  action  of  saprophytic  bacteria  under  favorable  con- 
ditions of  heat  and  moisture.  While  other  kinds  of  dust 
will  prevent  the  decay,  flowers  of  sulphur  is  preferable  as 


212  The  Potato 

it  has  fungicidal  properties.  Indeed,  it  has  been  shown 
that  when  sulphur  is  used  in  sufficient  quantities,  it  aids  in 
the  reduction  of  powdery  and  common  scab.  Gypsum 
makes  a  satisfactory  material  for  dusting,  but  lime  in  any 
form  should  not  be  used  for  this  purpose  as  it  may  induce 
scab. 

Disease  from  organisms  already  in  soil 

It  must  be  remembered  that  seed  treatment,  while  it 
destroys  certain  pathogenic  organisms  on  the  surface  of 
the  tuber,  does  not  insure  immunity  of  the  crop  from  these 
diseases.  Many  of  these  organisms  also  live  in  the  soil 
from  year  to  year,  and  these  are  as  able  to  attack  plants 
coming  from  treated  as  from  the  untreated  seed.  The 
treated  seed  must  be  planted  in  soil  that  is  free  from  these 
organisms  or  where  they  are  much  reduced  or  in  an  in- 
active condition.  It  is  impractical  to  sterilize  soil  for 
growing  potatoes,  although  for  greenhouse  and  other 
valuable  crops  it  is  considered  to  be  a  good  practice. 
The  application  of  chemicals  to  the  soil  that  will  destroy 
or  retard  the  growth  of  these  organisms  has  not  given 
very  satisfactory  results.  Sulphur  applied  at  the  rate  of 
450  to  900  pounds  to  the  acre  has  reduced  the  amount  of 
scabby  tubers  to  a  considerable  extent,  but  it  may  also 
reduce  the  yield.  It  has  been  observed  that  clover  will 
not  grow  in  soil  treated  in  this  way.  Fertilizers  such 
as  lime,  which  increase  the  alkalinity  of  the  soil,  greatly 
favor  the  development  of  scab,  while  acid  phosphate,  sul- 
phate of  ammonia  and  the  like,  at  least,  do  not  increase 
scab  injuries. 

When  potatoes  are  grown  year  after  year  upon  the 
same  land,  the  parasites,  especially  those  that  live  in  the 
soil,  are  likely  to  increase  unless  one  constantly  guards 


Control  Measures  213 

against  them.  On  the  other  hand,  if  the  potato  crop  is 
alternated  with  other  crops  or  can  be  grown  in  a  three- 
to  five-year  rotation,  these  parasites  depending  upon  the 
potato  for  food  will  be  starved  out  during  the  intervening 
years.  Unless  such  parasites  are  introduced  again  by 
planting  affected  seed,  or  with  manure  containing  these 
organisms,  or  with  infected  soil  washed  or  carried  on  to 
the  land,  the  potato  crop  planted  in  a  rotation  should  be 
comparatively  free  from  them. 

This  would  be  the  case  were  it  not  the  habits  of  some 
organisms  like  Rhizoctonia  to  live  on  hosts  other  than 
the  potato,  or  of  others  like  the  scab  organism  to  live 
from  year  to  year  on  dead  organic  matter  in  the  soil. 
However,  a  rotation  aids  in  reducing  these  organisms 
when  they  are  troublesome,  and  for  this  reason,  if  for  no 
other,  should  be  practiced  when  possible. 

Often  there  are  a  large  number  of  missing  hills  in  a 
field  caused  by  the  decay  of  the  seed  tuber  from  attacks 
of  Rhizoctonia,  or  for  other  reasons,  causing  the  total 
yield  to  be  materially  reduced.  This  is  especially  true 
when  the  tubers  are  planted  in  hills  or  at  distances  greater 
than  18  inches  in  the  row.  When  the  tubers  are  planted 
close  together,  a  missing  hill  does  not  mean  a  complete 
loss,  because  the  neighboring  hills,  having  more  room  for 
growth,  w^ill  produce  a  larger  yield.  Some  farmers  have 
found  it  profitable  to  replant  missing  hills  with  tubers 
that  have  been  greened,  i.e.  left  in  the  light  so  that  they 
have  stubby  green  sprouts.  Such  tubers  when  planted  grow 
rapidly  and  are  not  much  later  than  the  ones  planted  first 
and  not  greened.  Greening  potatoes  is  a  good  practice,  for 
such  tubers  will  give  a  better  stand  than  those  not  greened. 

There  are  diseases,  such  as  early  and  late  blight,  that 
occur  under  favorable  weather  conditions  and  do  much 


214  The  Potato 

damage  even  though  the  seed  has  been  carefully  selected 
and  treated  and  other  precautions  taken. 

Treatment  for  potato  blight 

The  blight-rot  fungus  is  not  destroyed  by  seed  treat- 
ment, and  slightly  affected  tubers  may  be  overlooked  in 
sorting.  Blight  spores,  being  easily  carried  by  air  cur- 
rents, are  readily  disseminated  from  one  field  to  another 
and  bring  about  an  infection  if  wet  weather  prevails.  It 
must  be  remembered  that  the  tubers  are  infected  by 
spores  produced  on  blighting  vines.  Hence,  to  prevent 
this  rot  from  occurring,  it  is  necessary  only  to  prevent 
the  vines  from  blighting.  The  vines  will  not  blight,  even 
under  very  favorable  weather  conditions,  if  the  spores  do 
not  gain  entrance  into  their  tissues.  The  spores  cannot 
enter  the  leaves  if  the  vines  are  thoroughly  sprayed  with 
bordeaux  mixture  before  the  spores  have  germinated. 
As  they  germinate  only  in  the  presence  of  moisture,  the 
applications  need  be  made  only  before  moist  conditions 
prevail,  that  is,  before  rainy  periods.  "The  grower  should 
not  hesitate  to  spray  at  such  times  for  fear  that  the  mix- 
ture will  be  washed  off.  It  dries  rapidly,  and  once  dried 
on  the  vines,  enough  remains  even  after  heavy  rains  to 
protect  them  from  the  fungus." 

Every  susceptible  part  of  the  vines  should  be  protected 
by  the  mixture.  To  do  this  eflFectively,  it  is  necessary 
that  the  mixture  should  come  from  the  nozzle  as  a  fine 
mist  and  settle  over  every  leaf  and  stem  like  a  fog.  Such 
a  mist  can  be  produced  with  a  satisfactory  nozzle  and 
with  good  pressure. 

One  application  thoroughly  done  will  protect  the  parts 
receiving  it  for  a  long  time,  but  new  leaves  appear,  and 


Control  Measures  215 

these  must  be  protected  by  subsequent  applications. 
These  applications  should  be  continued  as  long  as  growth 
of  the  vine  takes  place.  Even  when  the  vines  cover  the 
space  between  the  rows  and  driving  through  will  injure 
them,  the  spraying  must  be  done.  Less  loss  will  result 
from  injured  vines  than  from  rotted  tubers.  On  loamy 
ground,  the  injury  to  the  vines  is  not  so  great  as  one  would 
think.  Some  ingenious  farmers  have  devised  a  means  of 
pushing  the  vines  away  from  the  wheels  by  attaching  rake 
teeth  on  each  side  of  each  wheel.  Manufacturers  of 
spraying  machinery  should  be  able  to  devise  some  means 
of  overcoming  this  objection  to  spraying. 

From  five  to  eight  applications,  depending  upon  weather 
conditions,  should  be  made  during  the  season.  The  first 
should  be  given  when  the  plants  are  six  to  eight  inches 
high  or  when  a  poison  is  applied  to  kill  the  bugs.  For 
the  early  applications  50  to  75  gallons  of  mixture  to  the 
acre  will  be  sufficient,  but  later  in  the  season  it  will  re- 
quire 100  gallons  or  more.  Enough  should  be  applied  to 
do  a  good  piece  of  work  even  though  it  takes  150  gallons. 
The  operator  should  determine  this.  Nozzles  capable  of 
delivering  this  amount  of  liquid  as  a  mist  must  be  the 
only  kind  employed,  although  pressure  has  much  to  do 
with  fineness  of  the  mist.  From  70  to  80  pounds  of 
pressure  will  make  a  fine  mist  with  vermorel  nozzles  if 
there  are  not  too  many  used  at  a  time,  while  it  will  take 
100  to  150  pounds  of  pressure  to  get  a  good  mist  w^ith  an 
equal  number  of  disk  nozzles.  But  the  vermorels  do  not 
have  the  capacity  that  disk  nozzles  do  and  more  are  re- 
quired to  do  the  same  work.  One  disk  nozzle  will  do 
good  work  at  first,  but  two  should  be  employed  later  on 
and  then  should  be  so  adjusted  that  the  spray  is  directed 
at  an  angle  rather  than  straight  down  upon  them.     The 


216  The  Potato 

pump  of  the  machine  should  be  capable  of  maintaining  a 
uniformly  high  pressure.  These  are  factors  that  must  be 
considered  in  buying  or  constructing  a  machine.  Other 
points  are  of  secondary  importance.  For  small  fields  of 
an  acre  or  less,  a  small  compressed  air  spray  may  be  used. 

The  operator  should  see  that  the  mixture  gets  on  to  the 
vines.  It  is  of  little  value  applied  to  the  soil.  It  occa- 
sionally happens  that  a  nozzle  becomes  clogged,  and  the 
vines  below  are  not  being  properly  sprayed.  One  cannot 
hope  to  spray  a  field  adequately  by  merely  driving  through 
it.  Much  depends  on  the  interest  taken  by  the  driver. 
One  can  best  determine  whether  the  application  is  thorough 
by  examining  the  vines  after  spraying  them. 

Various  strengths  of  bordeaux  mixture  have  been 
recommended.  The  5 :  5  :  50  formula  is  commonly  used 
on  potatoes.  Experiments  have  shown  that  the  spores 
of  the  blight  fungus  can  be  prevented  from  germinating 
at  a  much  weaker  strength,  so  that  there  is  little  doubt 
that  the  blight  can  be  controlled  with  bordeaux  mixture 
at  2  :  2  :  50  or  3  :  3  :  50.  When  copper  sulphate  is  very 
expensive,  as  at  present,  larger  profit  can  doubtless  be 
secured  with  a  weaker  mixture  than  with  a  stronger  one, 
which  may  give  slightly  increased  yields  from  greater 
stimulation. 

For  many  years  potato  spraying  experiments  have 
been  conducted  in  several  states.  The  bordeaux  mix- 
ture has  been  prepared  in  various  ways,  and  used  at 
different  strengths.  The  experiments  have  been  con- 
ducted on  experiment  station  grounds  and  on  farms  in 
various  parts  of  the  country.  These  applications  have 
been  made  by  scientific  men  and  by  farmers  with  hand 
machines  and  with  traction  sprayers.  The  conclusion  in 
nearly  every  case  has  been  that  it  pays  to  spray  with 


Control  Measures  217 

bordeaux.  There  have  been  years  when  certain  fields 
have  shown  no  increase  from  spraying,  but  usually  a  suffi- 
cient increase  has  been  obtained,  if  the  spraying  has  been 
well  done,  to  pay  for  the  cost  of  the  applications.  Even 
in  years  when  the  blight  is  absent,  the  application  of  bor- 
deaux appears  to  stimulate  the  vines,  for  they  are  greener 
and  remain  alive  longer  than  unsprayed  vines.  Bordeaux 
also  acts  as  a  repellant  to  the  flea-beetle  and  reduces  the 
amount  of  tip-burn  and  so  protects  the  leaves  from  vari- 
ous injuries.  In  years  when  blight  is  present,  the  evi- 
dence is  greatly  in  favor  of  spraying.  One  cannot  tell 
with  any  certainty  when  blight  will  come,  so  one  should 
practice  spraying  as  a  protection.  Growers  should  accept 
the  evidence  and  make  spraying  of  potatoes  with  bordeaux 
a  general  farm  practice  every  year  whether  wet  or  dry  on 
both  early  and  late  varieties. 

Preparation  of  hordeailx  mixture  (See  Plate  XIII) 

Bordeaux  mixture  can  be  purchased  on  the  market  as 
a  paste  or  powder.  Usually  most  of  the  proprietary  mix- 
tures contain  in  addition  an  arsenical  poison  for  killing 
biting  insects.  They  are  prepared  for  spraying  by  the 
simple  addition  of  water  to  a  given  quantity  of  material. 
For  this  reason  they  are  convenient  to  use  and  also  safer 
when  one  needs  to  depend  on  irresponsible  help  to  do  the 
work.  However,  these  do  not  stay  in  suspension  as  well 
as  bordeaux  properly  made  at  home,  and  they  are  more 
expensive.  Home-made  bordeaux,  according  to  most 
comparative  experiments,  is  the  most  satisfactory.  Its 
preparation  is  easy  and  inexpensive  and  one  requires  but 
a  short  time,  when  the  apparatus  for  making  it  is  once 
constructed.     The  following  directions  with  a  few  addi- 


218  The  Potato 

tions  are  taken  from  the  New  York  Cornell  Agricultural 
Experiment  Station,  Circ.  19,  1913. 

The  best  bordeaux  mixture  is  made  by  mixing  a  dilute 
solution  of  copper  sulphate  (blue  vitrol)  with  a  dilute  milk- 
of-lime.  The  mixture  may  be  made  of  various  strengths 
by  using  different  amounts  of  copper  sulphate  and  lime  to 
a  given  amount  of  water.  A  combination  of  3  pounds 
of  copper  sulphate  and  3  pounds  of  lime  to  50  gallons 
of  water  is  probably  strong  enough  to  control  the  blight, 
but  because  of  the  stimulating  action  of  bordeaux  mixture 
on  the  potato  plant,  a  strength  of  5  pounds  each  of 
copper  sulphate  and  lime  to  50  gallons  of  water  is  usually 
recommended.  This  is  indicated  by  the  formula  5  :  5  :  50. 
In  order  to  make  the  bordeaux  mixture  of  any  strength, 
the  procedure  should  be  as  follows  :  — 

A  stock  solution  of  copper  sulphate  should  be  made  in  a 
barrel  from  45  pounds  of  copper  sulphate  dissolved  in  45 
gallons  of  water.  A  gallon  of  the  solution  will  then  con- 
tain about  one  pound  of  copper  sulphate.  If  the  crystals, 
placed  in  a  gunny  sack,  are  suspended  so  as  to  be  slightly 
beneath  the  surface  of  the  water,  they  will  dissolve  in 
three  or  four  hours. 

A  stock  mixture  of  lime  should  be  made  from  a  bushel 
of  good  stone  lime  placed  in  a  barrel  and  slaked  by  the 
gradual  addition  of  water.  Care  must  be  taken  not  to 
"drown"  the  lime.  When  it  has  become  pulverized  by 
the  slaking,  water  is  added  to  make  a  paste,  and  then 
enough  more  water  may  be  added  to  make  45  gallons. 
This  should  not  be  allowed  to  dry  out.  Hydrated  lime 
(which  is  already  slaked)  may  be  used  in  place  of  stone 
lime,  but  air-slaked  lime  should  never  be  used. 

Another  barrel  or  larger  container  or  even  the  sprayer 
tank  itself  may  be  used  for  mixing  the  bordeaux.     What- 


Control  Measures  219 

ever  container  is  used  should  be  filled  three-fourths  full 
of  water.  If  a  5  : 5  :  50  solution  is  desired,  5  gallons  of 
copper  sulphate  stock  solution  should  be  added  to  this 
water  for  every  50  gallons  of  mixture  to  be  made.  The 
solution  requires  stirring  until  it  is  well  diluted,  after 
which  5  gallons  of  the  stock  mixture  of  milk-of-lime  should 
be  added  to  each  50  gallons  of  mixture.  The  lime-water 
should  be  run  through  a  strainer  in  order  to  prevent  the 
larger  particles  of  lime  from  getting  into  the  sprayer  tank. 
While  the  milk-of-lime  is  being  added  to  the  dilute  copper 
sulphate  solution  in  the  sprayer  tank,  the  material  in  the 
container  should  be  stirred  constantly.  The  sky-blue 
bordeaux  mixture  will  result.  Enough  water  to  make  the 
required  amount  of  mixture  must  be  added  to  it. 

It  is  often  more  convenient,  although  not  necessary,  to 
make  the  bordeaux  on  an  elevated  platform  so  as  to  allow 
the  mixture  to  run  by  gravity  into  the  sprayer  tank  (see 
Plate  XIII).  When  such  a  platform  is  provided,  it  is  easily 
possible  to  dilute  both  the  stock  copper  sulphate  solution 
and  the  stock  lime  solution  in  separate  containers  before 
mixing  them  by  allowing  them  to  run  together.  This 
method  makes  a  bordeaux  that  stays  in  suspension  a  little 
better  than  that  made  by  diluting  but  one  stock  before 
mixing.  In  case  the  latter  method  is  used  the  required 
amount  of  stock  in  each  case  should  be  diluted  with  one- 
half  the  amount  of  water  necessary  to  make  the  mixture. 

The  mixture  should  now  be  tested  with  a  few  drops 
of  a  solution  of  potassium  ferrocyanide.  This  is  made 
from  crystals  of  potassium  ferrocyanide  dissolved  in  soft 
water.  Five  cents'  worth  of  crystals  dissolved  in  a  pint  of 
water  will  provide  enough  of  the  solution  to  last  through- 
out the  season.  Should  a  brown  precipitate  result  when 
a  few  drops  of  this  solution  are  added  to  the  bordeaux 


220  -  The  Potato 

mixture,  it  would  indicate  that  more  lime-milk  is  needed 
to  neutralize  the  copper  sulphate  solution.  When  suffi- 
cient lime  is  added,  no  brown  precipitate  will  be  formed 
by  the  potassium  ferrocyanide  solution.  Bordeaux  mix- 
ture will  burn  the  foliage  of  plants  if  it  is  not  properly 
neutralized.  It  is  unnecessary  to  measure  the  milk-of- 
lime  in  making  bordeaux  mixture  if  the  mixture  is  tested 
from  time  to  time  with  the  ferrocyanide  solution  while 
adding  the  lime.  The  test  will  indicate  when  sufficient 
lime  is  present. 

When  it  is  necessary  to  spray  with  a  poison  in  order 
to  kill  potato  beetles  and  other  biting  insects,  the  re- 
quired amount  of  poison  may  be  added  to  the  bordeaux 
mixture. 

Other  remedies 

Soda  bordeaux,  in  which  an  equal  amount  of  sal-soda  is 
used  in  place  of  lime,  has  been  employed  by  some  potato- 
growers,  but  carefully  conducted  experiments  indicate 
that  other  preparations  wdth  copper  compounds  are  in- 
ferior to  lime.  Dry  bordeaux  applied  as  a  dust  has  not 
proved  to  be  a  satisfactory  fungicide.  Lime  sulphur  solu- 
tion is  also  unsatisfactory  and  unsafe.  Where  it  has 
been  used  in  experimental  work,  potato  plants  sprayed 
with  it  have  given  smaller  yields  than  the  unsprayed  ones. 
Powdered  sulphur  and  arsenate  of  lead  or  arsenate  of  zinc 
have  been  tried  in  New  Jersey  on  early  potatoes,  but  have 
been  found  to  be  less  satisfactory  and  more  expensive 
than  bordeaux  mixture. 

Fusarium  dry  rot  and  other  rots  are  caused  by  organ- 
isms that  gain  entrance  to  the  tuber  through  wounds. 
Potatoes  with  tender  skin  loaded  into  cars  in  hot  weather 
soon  after  digging  often  rot  badly.     Care  in  handling  the 


Control  Measures  221 

tubers  is  necessary  if  one  wishes  to  avoid  these  troubles. 
Provisions  for  ventilation  should  be  made  when  the  tubers 
are  placed  in  storage.  A  potato  tuber  contains  living 
protoplasm  which  gives  off  carbon  dioxide,  water  and 
a  certain  amount  of  heat,  and  when  provision  is  not  made 
for  ventilation,  black-heart  or  center  decay  may  occur. 

Disease-resistant  varieties 

These  various  control  measures  have  been  discussed 
because  it  is  necessary  to  adopt  some  or  all  of  them  if  one 
is  to  grow  healthy  tubers.  However,  each  practice  adds 
to  the  cost  of  producing  the  crop.  If  such  measures  do 
not  increase  the  yield  or  add  to  the  value  of  the  tubers, 
they  are  not  worth  putting  into  practice.  If  it  were  pos- 
sible to  obtain  potatoes  that  would  not  become  diseased 
even  when  subjected  to  the  parasite  under  favorable  con- 
ditions for  infection,  much  labor  and  expense  would  be 
saved.  It  is  well  known  that  certain  individual  plants  as 
well  as  animals  have  shown  marked  resistance  to  diseases 
that  ordinarily  occur  on  their  kind.  By  selection  and 
breeding,  it  has  been  possible  to  obtain  highly  resistant 
plants  producing  crops  of  good  quality.  Notable  ex- 
amples are  wilt-resistant  melons,  cotton  and  flax,  rust- 
resistant  wheat  and  anthracnose-resistant  beans.  For 
several  years  scientists  have  been  endeavoring  to  secure 
a  satisfactory  strain  or  variety  of  potatoes  that  is  blight 
resistant.  Some  varieties  have  been  secured  that  have 
shown  a  fair  degree  of  resistance  to  blight  or  rot.  Unfor- 
tunately, a  variety  that  seems  to  show  a  slight  degree  of 
resistance  to  blight  may  show  considerable  susceptibility 
to  rot,  and  varieties  showing  resistance  to  early  blight 
may  be  subject  to  late  blight.     William  Stuart  of  the 


222  The  Potato 

Department  of  Agriculture,  Washington,  D.  C,  has 
reported  certain  varieties  that  have  shown  considerable 
resistance  to  both  early  and  late  blight.  These  are 
Apollo,  Sophia,  Professor  Wohltman  and  Max  Eyth. 
They  are  all  foreign  varieties  and  under  conditions  of 
climate  and  soil  in  the  United  States  they  succeed  very 
poorly,  being  light  yielders  and  rather  poor  in  quality. 
Stuart  remarks  that  it  would  seem  as  if  high  disease- 
resistance  of  the  vine  was  correlated  with  low  yield  and 
undesirable  tubers.  He  found  no  varieties  tested  to  have 
strongly  marked  scab-resistant  qualities  when  grown  in 
soil  well  infested  with  the  scab  organisms.  He  believes 
that  the  value  of  disease-resistant  varieties  is  problem- 
atical, but  that  the  plant-breeder,  by  mating  them  with 
the  most  desirable  commercial  American  types,  may 
develop  commercial  types  of  resistant  varieties. 

Summary 

It  may  be  well  to  summarize  control  measures  in  the 
following  way :  — 

What  selection  does.  —  It  aids  in  eliminating  curly- 
dwarf,  leaf-roll,  mosaic,  the  various  wilts,  black-leg  and 
other  diseases  showing  on  the  vines  and  also  transmitted 
by  the  tuber.  It  eliminates  low-yielding  hills.  It  elimi- 
nates impurities  in  a  variety. 

What  seed  treatment  and  rotation  do.  —  They  reduce  in- 
jury from  rhizoctoniose,  scabs  and  black-leg.  They 
increase  the  stand  of  potatoes  in  the  field.  They  give 
clean  tubers. 

What  spraying  does.  —  It  prevents  early  and  late 
blight.  It  prevents  the  blight  rot.  It  reduces  injury 
from  tip-burn.     It  repels  flea-beetles.     It  kills  the  bugs. 


Control  Measures  223 

It  stimulates  the  vines  to  longer  periods  of  growth.     It 
gives  increased  yields. 


REFERENCES 

DUGGAR,    B.   M. 

1909.     Fungous  Diseases  of  Plants.     (Ginn  &  Co.),  1-508,  Figs. 
1-240. 
Gloyer,  W.  O. 

1913.  The  Efficiency  of  Formaldehyde  in  the  Treatment  of  Seed 

Potatoes  for  Rhizoctonia.     New  York  (Geneva)  Agri. 

Expt.  Sta.  Bui.  370 :  417^31,  pi.  1. 
Jones,  L.  R. 

1899.     Certain  Potato  Diseases  and  Their  Remedies,     Vt.  Agri. 

Expt.  Sta.  Bui.  72  :  3-32,  Figs.  1-17. 
Jones,  L.  R.,  Giddings,  N.  J.,  and  Lutman,  B.  F. 

1912.  Investigations    of    the    Potato    Fungus.     Phytophthora 

Infestans.     U.  S.  D.  A.,  Bur.  PI.  Ind.,  Bui.  245  :  5-100, 

Figs.  1-10. 
Lutman,  B.  F. 

1911.     Twenty    Years    Potato    Spraying    for    Potato    Disease. 

Potato  Diseases  and    the   Weather.     Vt.  Agri.    Expt. 

Sta.  Bui.  159  :  215-296. 
Lutman,  B.  F.,  and  Cunningham,  G.  C. 

1914.  Potato  Scab.     Vt.  Agri.  Expt.  Sta.  Bui.  184 :  3-64,  Figs. 

1-6,  pis.  1-12. 
Mann,  Thos.  F. 

1911.     The  Fusarium  Blight  Wilt  and  Dry  Rot  of  the  Potato. 
Ohio  Agri.  Expt.  Sta.  Bui.  229  :  229-336,  pis.  1-15. 
McAlpine,  D. 

1911.     Handbook  of  Fungous  Diseases  of  the  Potato  in  Australia 
and  Their  Treatment,  with  158  figures.     Dept.  of  Agri- 
culture, Victoria. 
Melhus,  L  E. 

1913.  Silver  Scurf —  A  Disease  of  the  Potato.     U.  S.  D.  A.,  Bur. 

PI.  Indus.,  Circ.  127:   15-24,  Figs.  1-4. 
Melhus,  I.  E. 

1914.  Powdery    Scab    (Spongospora    subterranea)    of    Potatoes. 

U.  S.^D.  A.,  Bui.  82 :  1-16,  pis.  1-2. 


224  Tlie  Potato 

Melhus,  I.  E. 

1915.  Hibernation  of  Ph\i;ophthora  Infestans  of  the  Irish  Potato. 

U.  S.  D.  A.,  Jour,  of  Agri.,  Research  Bui.  5  :  71-102,  Figs. 
1-3,  pis.  4-8. 
Melhus,  I.  E. 

1916.  Germination  and  Infestion  with  the  Fungus  of  the  Late 

Blight  of  Potato.     Wisconsin  Agri.  Expt.  Sta.,  Research 
Bui.  37:  1-64,  Figs.  1-8. 
Morse,  W.  J. 

1909.     Black-leg  —  A    Bacterial    Disease    of    the    Irish    Potato. 
Maine  Agri.  Expt.  Sta.  Bui.  174  :  309-328. 
Morse,  W.  J.,  and  Shapovaloy,  M. 

1914.     The  Rhizoctonia   Disease   of  the   Potato.     Maine   Agri. 
Expt.  Sta.  Bui.  230 :  193-216,  Figs.  61-73. 
Morse,  W.  J. 

1914.     Powdery  Scab  of  Potatoes.     Maine  Agri.  Expt.  Sta.  Bui. 
227  :  89-104,  Figs.  44-50. 
MuNN,  M.  T. 

1912.  Lime  Sulfur  vs.  Bordeaux  Mixture  as  a  Spray  for  Potatoes. 

Part  II.     New  York   (Geneva)  Agri.  Expt.  Sta.  Bui. 
352 :  319-326. 
Orton,  W.  a. 

1913.  Potato  Tuber  Disease.     U.  S.  D.  A.,  Farmers'  Bui.  544 : 

3-16,  Figs.  1-16. 
Orton.  W.  A. 

1914.  Potato  Wilt,  Leaf  Roll  and  Related  Disease.     U.  S.  D.  A., 

Bui.  64 :  1^8,  pis.  1-14. 
Smith,  E.  F.,  and  Swingle,  D.  B. 

1904.     The  Dry  Rot  of  Potatoes  due  to  Fusarium  Oxysporum. 
U.  S.  D.  A.,  Bm-.  Pi.  Indus.,  Bui.  55 : 3-64,  pis.  1-8. 
Smith,  E.  F. 

1896.     A  Bacterial  Disease  of  the  Tomato,  Eggi)lant  and  Irish 
Potato.     U.  S.  D.  A.,  Div.  Veg.  Phys.  and  Path.,  Bui. 
12 :  3-25. 
Stevens,  F.  L.,  and  Hall,  J.  G. 

1913.     Diseases   of   Economic   Plants.      (The   Macmillan   Co.), 
New  York,  1-513,  Figs.  1-214. 
Stewart,  F.  C,  French,  G.  T.,  and  Sirrine,  F.  A. 

1912.      Potato  Spraying  Experiments  — 1902-1911.     New  York 
(Geneva)  Agri-  Expt.  Sta.  Bui.  349  :  99-139. 


Control  Measures  225 

Stewart,  F.  C,  and  Gloyer,  W.  O. 

1913.  The   Injurious  Effect   of   Formaldehyde  Gas  on   Potato 

Tubers.     New  York  (Geneva)  Agri.  Expt.  Sta.  BuL  369  : 
385-416,  pis.  1-2. 
Stewart,  F.  C.,  and  Sirrine,  F.  A. 

1915.  The  SpindHng  Sprout  Disease  of  Potatoes.      New  York 

(Geneva)  Agri.  Expt.  Sta.  Bui.  399  :  133-143,  pis.  1-3. 
Stewart,  F.  C. 

1916.  Observations  on    Some    Degenerate   Strains   of   Potatoes. 

New  York  (Geneva)    Agri.    Exp.   Sta.   Bui.  422:319- 
357,  Pis.  1-12. 
Stuart,  Wm. 

1914.  Disease  Resistance  of  Potatoes.       Vt.  Agri.  Expt.  Sta. 

Bui.  179  :    147-173,  Figs.  1-8. 


CHAPTER  XII 
HARVESTING    THE  POTATO 

There  are  several  important  considerations  bearing 
upon  the  harvesting  of  the  potato  crop.  These  must  be 
kept  in  mind  when  one  is  phmning  the  time  and  method 
of  harvesting,  if  the  best  returns  are  to  be  reaUzed.  Im- 
proper attention  to  any  of  these  points  may  result  in  a 
very  material  decrease  in  the  crop. 

In  the  first  place,  the  harvesting  should  be  done  at  such 
a  time  and  in  such  a  manner  as  to  give  the  maximum 
yield  of  tubers  possible  for  that  season.  This  means  that 
we  are  to  let  the  processes  of  starch  formation  and  storage 
go  on  as  long  as  they  will.  Secondly,  we  should  aim  to 
employ  such  methods  as  will  give  us  potatoes  of  the  best 
cooking  and  keeping  qualities.  And  thirdly,  we  must 
eliminate,  as  far  as  possible,  all  traces  of  disease  from  the 
crop.  Each  operation  in  the  process  of  harvesting  should 
be  carried  on  with  careful  consideration  of  its  effect  on 
total  yield,  quality  and  disease. 

Time  to  harvest 

The  time  of  harvesting  is  influenced  by  the  weather 
conditions  and  by  the  kind  of  potatoes  grown.  In  general, 
one  does  not  need  to  be  as  particular  with  early  potatoes 
as  with  the  late  varieties.  Early  potatoes  may  be  dug 
as  soon  as  they  are  large  enough  to  eat.  Late  potatoes, 
226 


Harvesting  the  Potato 


227 


generally  speaking,  should  be  left  in  the  ground  as  long 
as  is  possible  without  freezing.  It  should  be  remembered 
that  starch  is  being  formed  and  stored  as  long  as  the  tops 
of  the  plants  are  green.  To  harvest  the  crop  before  the 
tops  die,  therefore,  means  a  loss  in  quantity  of  potatoes. 
Early  varieties  may  be  dug  a  week  or  two  before  maturity, 
providing  the  higher  price  a  bushel  more  than  compen- 
sates for  the  decrease  in  yield.  Late  potatoes,  which 
are  usually  stored  for  part  or  all  of  the  winter,  should 
preferably  be  fully  mature  and  in  good  condition  when 
harvested. 

Kohler,^  of  the  Minnesota  Experiment  Station,  presents 
some  interesting  data  on  the  results  of  digging  potatoes 
during  the  period  of  development.  The  variety  on  which 
the  studies  were  made  was  the  Early  Ohio.  The  tubers 
were  planted  by  hand  on  June  3,  and  the  diggings  were 
begun  about  two  months  later  and  continued  at  intervals 
of  about  a  week,  until  the  tops  of  the  plants  had  died  : 

Table  XII.  —  Results  from  Digging  Early  Ohio  Potatoes 
AT  Intervals  during  the  Period  of  Development 

(In  Bushels  to  the  Acre) 


Date  op 
Digging 

IK 

3 

i 
> 

a 

w 
« 

1 

a 

H 

July  31 



10.9 





1.2 

9.7 

27.8 

38.7 

0 

Aug.    7 

7.5 

62.3 

— 

3.3 

30.5 

28.5 

25.4 

87.7 

1 

Aug.  14 

7.6 

115.4 

— 

29.3 

59.5 

26.1 

26.1 

141.5 

8 

Aug.  23 

7.2 

182.1 

6.7 

42.9 

97.3 

35.2 

21.1 

203.2 

22 

Aug.  30 

6.4 

226.8 

6.7 

93.5 

92.8 

33.8 

27.0 

253.8 

99 

•  Minn.  Bui.  118. 


228  The  Potato 

The  plants  took  practically  three  months  to  mature. 
Three  weeks  of  this  time  were  taken  up  in  coming  through 
the  soil.  About  five  more  weeks  were  consumed  by  the 
crop  in  getting  ready  to  produce  tubers.  Most  of  the 
potatoes  are  produced  during  the  last  month  of  growth. 
During  this  last  month,  there  was  a  daily  gain  of  about 
7  bushels  of  marketable  tubers  to  the  acre  —  up  to  the 
time  the  vines  died. 

The  potatoes  were  classified  as  to  size  on  the  following 
basis : 

Small  —  1§  ounces  or  less. 
Near  small  —  2  ounces  to  1^  ounces. 
Medium  —  5  ounces  to  2|  ounces. 
Large  —  9  ounces  to  5  ounces. 
Very  large  —  over  9  ounces. 

This  table  warrants  the  conclusion  that  potatoes  should 
be  harvested  after  the  tops  die,  if  we  are  to  secure  the 
highest  yield.  It  also  shows  that  there  is  a  loss  of  yield 
if  we  harvest  the  crop  before  it  is  mature,  and  that  this 
loss  increases  with  the  increase  of  time  between  the  date 
of  harvesting  and  the  time  of  maturity. 

In  the  case  of  early  potatoes,  it  is  often  possible  to 
obtain  prices  high  enough  to  overbalance  the  loss  in  yield 
and  to  make  it  profitable  to  dig  them  before  they  are 
mature. 

Table  XIII  has  been  arranged  from  figures  given  by 
Kohler,  to  show  relative  prices  at  which  potatoes  should 
sell  if  dug  one  and  two  weeks  before  maturity. 

Potatoes  which  are  harvested  before  the  tops  die  and 
before  the  tubers  can  be  easily  separated  from  the  stems 
are  usually  immature.  Such  potatoes  are  not  up  to  the 
American  standard  of  quality  for  cooking,  and  are  almost 


Harvesting  the  Potato 


229 


sure  to  disappoint  the  buyer.  The  immature  tubers  are 
also  poorer  in  keeping  qualities  than  those  which  have 
matured  on  the  vines. 


Table   XIII.  —  Early  Digging  for  Market 


Price   when 
Mature 

Prices  Which  Must  Be  Obtained  if  Potatoes  Are  Dug 

1  Week  before  Mature 

2  Weeks  before  Mature 

25  i 
50)4 

30^ 
Mi 
63  ff 

AH 

59  ff 
86)4 

For  several  reasons  it  is  best  to  harvest  potatoes  in  dry, 
cool  weather.  The  tubers  should  be  dug  when  the  soil 
is  fairly  dry,  in  order  that  they  may  go  into  storage 
in  a  dry  condition  and  as  free  from  dirt  as  possible.  The 
cool  weather  prevents  their  wilting  unduly  and  makes 
it  possible  to  get  them  into  storage  in  good  condition. 
If  the  soil  is  not  too  moist,  potatoes  are  best  left  in  the 
ground  for  a  time  after  the  tops  have  died,  at  least  until 
there  is  danger  of  a  freeze.  Most  authorities  agree  that 
no  harm  results  from  such  a  practice  as  long  as  the  soil 
condition  is  as  described.  In  some  sections  this  may  be 
almost  necessary,  especially  where  several  weeks  of  warm 
weather  are  likely  to  follow  the  dying  of  the  vines.  It  is 
difficult  to  store  potatoes  successfully  if  there  are  two 
or  three  weeks  of  warm  weather  immediately  after  they 
have  been  put  into  storage.  In  the  North,  cold  weather 
usually  follows  the  dying  of  the  vines  so  closely  that  it  is 
best  to  dig  and  store  as  soon  as  the  tops  die,  and  occasion- 
ally the  digging  must  be  done  while  the  plants  are  still 
green  in  order  to  save  the  tubers  from  freezing.     Where 


230  The  Potato 

there  is  any  disease  in  the  crop,  the  practice  of  leaving  the 
tubers  in  the  ground  for  a  time  after  they  have  matured 
has  a  distinct  advantage.  The  infected  tubers  start  to 
rot  in  the  ground,  and  when  they  are  dug  they  can  easily 
be  discarded.  Otherwise  they  are  stored  with  the  sound 
potatoes  and  frequently  cause  a  great  deal  of  rotting. 

The  progressive  grower  of  potatoes  will  have  on  his 
farm  a  breeding  plot  on  which  he  is  attempting  to  isolate 
one  or  two  superior  strains  of  the  variety  which  he  is 
growing.  He  ought  to  be  constantly  on  the  watch  for 
plants  which  show  promise,  and  bring  in  the  tubers  pro- 
duced by  these  for  a  tuber-unit  test.  Some  time  during 
the  growing  season  the  farmer  should  go  through  his 
commercial  field  and  stake  any  plants  which  show  quali- 
ties of  unusual  vigor,  disease-resistance,  desirable  habit 
and  so  on.  The  product  of  such  plants  should  be  dug 
by  hand,  bagged  separately  and  records  taken  as  to 
uniformity,  size,  weight  and  so  on.  A  consideration  of 
the  data  taken  on  each  plant  will  show  the  grower  whether 
or  not  he  should  keep  the  tubers  for  further  growing  and 
selection. 

Methods  of  digging 

The  method  employed  in  getting  potatoes  out  of  the 
soil  will  depend  a  great  deal  on  the  area  planted,  the 
type  of  soil  and  the  cheapness  of  labor.  Formerly,  all 
potatoes  were  dug  by  hand  with  spades  or  forks.  Later 
on,  many  growers  used  an  ordinary  plow  to  lift  them. 
Then  a  special  type  of  plow,  the  shovel  plow,  was  em- 
ployed. Later  came  the  various  types  of  mechanical 
diggers. 

Small  plantings  of  potatoes  must  always  be  dug  by 
hand,  because  of  the  high  cost  of  the  digging  machines. 


Harvesting  the  Potato  231 

It  is  often  necessary,  also,  to  dig  early  potatoes  by  hand. 
In  the  early  varieties  the  skin  is  tender  and  easily  in- 
jured by  the  digging  machinery.  The  tubers  also  cling 
to  the  underground  stems  and  frequently  have  to  be 
pulled  off.  A  man  will  dig  from  ^  to  |  acres  a  day, 
depending  on  the  yield  and  type  of  soil. 

Digging  by  plows  is  not  to  be  recommended  unless  it 
is  a  case  of  getting  part  of  the  crop  or  none.  The  plows 
cut  and  otherwise  injure  many  of  the  tubers,  and  they 
cover  nearly  as  many  potatoes  as  they  turn  up.  Growers 
usually  agree  that  hand-digging  secures  enough  more 
potatoes  than  plowing  to  make  the  extra  labor  well  worth 
while. 

When  the  planting  is  relatively  large,  it  pays  the  grower 
to  buy  a  good  digging  machine.  Such  machines  work 
quickly  and  are  usually  very  satisfactory.  In  heavy 
soils  and  stony  soils,  and  in  cases  in  which  the  plantings 
are  deep,  there  is  a  question  as  to  their  efficiency. 

The  type  of  machine  commonly  used  in  this  country 
has  a  steel  nose  which  runs  under  the  row  and  lifts  potatoes 
and  soil  onto  a  grating  of  iron  rods.  The  soil  falls  through 
the  grating  and  the  potatoes  travel  along  the  rods  and 
are  dropped  at  the  back  of  the  machine  on  top  of  the 
ground.  From  two  to  four  horses  are  used  on  such  a 
machine.  A  good  machine  will  dig  from  3  to  6  acres  of 
potatoes  a  day,  and  will  keep  from  10  to  15  men  busy 
picking  them  up.  A  second  type  of  digger,  less  com- 
monly used,  has  a  revolving  frame  with  forks  which  dig 
into  the  ground  at  right  angles  to  the  row.  Potatoes 
and  soil  are  thrown  against  a  screen  and  the  soil  passes 
through,  leaving  the  potatoes  in  a  row  upon  the  ground. 

When  a  digging  machine  is  used,  it  is  sometimes  neces- 
sary to  remove  the  dead  vines  from  the  rows  before 


232  The  Potato 

digging.  This  can  be  done  by  running  a  spike-toothed 
harrow  across  the  field  lengthwise  of  the  rows.  It  has 
the  added  advantage  of  leveling  off  the  ground  where 
the  soil  has  been  hilled  up  about  the  plants. 

Picking  and  sorting 

It  is  usually  considered  best  to  let  the  tubers  dry  on 
the  ground  for  two  to  six  hours  before  picking  them  up. 
This  results  in  a  drying  and  falling  off  of  the  excess  dirt 
and  also  toughens  the  skin  and  lessens  its  liability  to  in- 
jury in  handling.  If  the  potatoes  are  left  for  too  long  a 
time  in  the  strong  sunlight,  they  turn  green  and  their 
eating  quality  is  injured. 

Potatoes  are  usually  picked  by  hand  into  bushel  baskets 
or  crates  (see  Plate  XIV).  Formerly  it  was  the  practice 
to  empty  these  containers  into  a  wagon  box  and  to  cart 
the  potatoes  to  the  storage,  where  they  were  shoveled 
into  boxes.  This  method  of  handling  usually  resulted  in 
considerable  injury  to  the  potatoes  and  greatly  impaired 
their  keeping  qualities.  At  present,  potatoes  are  usually 
hauled  from  the  field  in  two-bushel  bags  or  in  one-bushel 
crates. 

Alva  Agee  ^  recommends  the  use  of  one-bushel  boxes 
for  carting  potatoes  from  the  field.  Such  boxes,  he  says, 
should  be  made  of  basswood  or  some  other  light  wood 
and  should  be  of  2688  cubic  inches  capacity.  These  boxes 
are  best  made  12i  inches  deep,  13i  inches  wide  and  16 
inches  long.  The  sides  and  bottom  should  be  f  inch 
thick  and  the  ends  i  inch  thick.  The  length  of  two  such 
boxes  is  about  equal  to  the  width  of  an  ordinary  wagon 
bed.     With  high  side-boards  on  the  wagon,  these  can  be 

1  Penn.  Dept.  of  Agr.  Bui.  105. 


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BmEN^Sa^wII 

IVRlMSirSii^SlllS 

Harvesting  the  Potato 


233 


piled  up  in  tiers  and  about  60  boxes  put  on  a  load.  Boxes 
of  this  description  can  be  purchased  for  about  18  cents 
each.  Slat  crates  of  cheaper  construction  can  be  had  for 
about  12  to  18  cents  each.  These  boxes  are  quite  dur- 
able and  with  proper  care  should  last  10  or  12  years. 

There  are  now  on  the  market  machines  which  dig  and 
bag  potatoes  in  one  operation.  Machines  of  this  sort 
undoubtedly  save  a  great  amount  of  labor,  and  in  some 


Fig.  17.     One  type  of  potato  sorter. 

cases  will  prove  to  be  good  investments.  We  should 
remember,  however,  that  potatoes  harvested  in  this 
manner  have  no  chance  to  dry  off  and  are  therefore  more 
likely  to  rot  in  storage  than  those  which  have  stood  for 
a  few  hours  on  the  surface  of  the  ground. 

Where  the  weather  will  permit,  it  is  usually  advisable 
to  sort  potatoes  in  the  field.  Various  types  of  sorting 
machines  are  used  for  this  purpose  (see  Fig.  17  and  Plate 
XV).  One  is  simply  a  wooden  frame  on  runners,  having 
two  inclined  sieves  of  heavy  wire.  The  largest  potatoes 
roll  down  the  top  sieve  into  a  sack  at  the  end.  The 
smaller  potatoes  fall  through  the  upper  sieve  on  to  a  finer 


234  The  Potato 

one,  and  the  larger  of  these  potatoes  roll  down  into  a  bag 
at  the  end  of  that  sieve.  The  very  small  potatoes  and 
pieces  of  dirt  fall  through  the  sorter  on  to  the  ground. 
A  horse  can  be  attached  to  this  sorter,  and  it  can  be  drawn 
around  the  field  as  the  men  pick. 

Other  sorters  of  a  more  complicated  type  are  often 
used  in  grading  potatoes,  but  most  of  these  are  too  cum- 
bersome to  be  hauled  about  for  field  sorting. 

Some  potato-growers  are  heartily  in  favor  of  washing 
potatoes  after  bringing  them  from  the  field.  This  is 
done  by  the  use  of  sprayers,  and  the  potatoes  are  poured 
on  to  racks  to  dry.  Those  who  advocate  washing  claim 
that  it  not  only  makes  the  tubers  more  marketable,  but 
that  it  also  reduces  the  loss  by  rotting  in  storage.  Other 
growers  insist  that  the  labor  of  washing  is  not  worth 
while,  and  still  others  say  that  it  is  injurious  to  the  potatoes 
to  wash  them.  Experimental  evidence  on  these  questions 
is  lacking. 

Labor  and  cost  of  harvesting 

It  is  difficult  to  make  an  exact  estimate  of  the  cost  of 
harvesting  an  acre  of  potatoes,  because  of  the  differences 
in  the  methods,  the  skill  of  the  laborers,  the  type  of  soil 
and  the  size  of  the  crop.  Only  approximate  figures,  there- 
fore, can  be  given. 

If  the  digging  is  done  by  hand,  i  to  i  an  acre  can  be 
dug  by  a  man  in  a  day.  Fraser  ^  estimates  the  cost  of 
such  digging  at  from  two  to  six,  or  even  eight,  cents  a 
bushel. 

A  machine  will  dig  from  3  to  6  acres  a  day.  If  we 
allow  three  dollars  a  day  for  the  use  of  the  team  and 
two  dollars  a  day  for  the  driver,  the  cost  of  digging  an 

»  S.  Fraser.     "The  Potato." 


Harvesting  the  Potato  235 

acre  by  machinery  will  vary  from  87  cents  to  $1.67.  As 
this  machine,  digging  between  3  and  6  acres  a  day,  keeps 
from  10  to  15  men  busy  picking,  it  would  appear  that 
about  3  men  are  needed  to  pick  up  the  potatoes  on  an 
acre. 

If  the  potatoes  are  sorted  in  the  field,  this  item  must  be 
added  in  figuring  the  cost  of  harvesting.  The  quantity 
which  can  be  sorted  in  one  day  will  depend  a  great  deal 
upon  the  type  of  sorter  used.  From  500  to  1000  bushels 
can  be  sorted  by  a  machine  in  one  day. 

It  is  almost  impossible  to  make  an  accurate  estimate 
of  the  cost  of  hauling  from  the  field  to  the  storage  cellar. 
The  size  of  the  wagon  used  and  the  distance  of  hauling 
will  vary  greatly,  and  even  an  approximation  of  the  cost 
of  this  operation  would  probably  be  valueless. 

The  grower  should  always  remember  that  the  care 
which  he  exercises  in  harvesting  his  crop  will  mean  an 
appreciable  difference  in  its  marketability.  Cut  and 
bruised  tubers  bring  a  lower  price  when  sold  directly 
from  the  field,  and  they  are  a  complete  loss  when  put  into 
storage.  Poor  judgment  as  to  time  and  method  of  har- 
vesting will  have  a  detrimental  effect  upon  yield  and 
upon  quality.  The  farmer  who  spends  time  and  money 
to  raise  a  good  crop  of  potatoes  should  be  equally  careful 
in  getting  his  crop  to  the  market  or  into  storage  in  the 
best  possible  condition. 

REFERENCES 
Agee,  Alva. 

1904.  Potato  Production.     Kansas  Agr.  Report. 
Agee,  Alva.     Penn.  Dept.  Agri.  Bui.  105. 

Bennett,  E.  R.  The  Colorado  Potato  Industry.  Colorado  Bui. 
Eraser,  Samuel. 

1905.  The  Potato.     N.  Y.  (Orange  Judd  Co.),  pp.  143-146. 


236  TJie  Potato 

Grubb,  E.  H.,  and  Guilford,  W.  S. 

1912.    The  Potato.    N.  Y.  (Doubleday,  Page  &  Co.),  pp.  111-118. 

KOHLER,   A.    p. 

1909.     Potato   Experiments   and   Studies  at  University  Farm. 
Minn.  Bui.  118. 
Macoun,  W.  T. 
The  Potato  and  its  Culture.    Central  Expt.  Farms,  Bui.  49. 


CHAPTER   XIII 
MARKETS,  MARKETING  AND  STORAGE 

It  is  of  interest  to  know  the  quantity  of  potatoes  which 
are  marketed  every  year  in  the  United  States,,  in  order 
to  appreciate  the  importance  of  the  marketing  problems. 
Such  a  figure,  of  course,  can  never  be  very  accurately  ob- 
tained, because  of  the  lack  of  statistics  of  various  sorts 
necessary  in  computing  it.  It  is  possible,  however,  to 
make  a  calculation  which  is  approximately  correct.  This 
figure  should  be  considered  only  as  an  approximation. 

The  following  table  of  averages  may  help  to  give  an  idea 
of  the  number  of  bushels  of  potatoes  which  are  marketed 
every  year  in  this  country  : 

Table  XIV.  —  Averages  for  1904-1913 

Annual  production 326,199,200  bu. 

Quantity  marketed  in  the  fall  —  50  per  cent    .  163,099,600  bu. 

Quantity  stored  —  50  per  cent 163,099,600  bu. 

8  per  cent  less  on  stored  potatoes       ....  13,047,968  bu. 

Quantity  used  for  starch 5,000,000  bu. 

Seed  needed  for  next  year 48,286,000  bu. 

Number  of  farms  raising  potatoes 3,008,474 

Potatoes  consumed  on  farms 75,211,850  bu. 

Bushels  to  be  marketed  (home  grown)    .     .     .  183,653,382  bu. 

Annual  imports  of  potatoes 2,688,148  bu. 

Annual  exports  of  potatoes 1,410,831  bu. 

Excess  of  imports  over  exports 1,277,317  bu. 

In  figuring  the  seed  needed,  14  bushels  of  potatoes  were 
allowed  to  the  acre.     The  number  of  farms  raising  pota- 
237 


238  The  Potato 

toes  is  an  average  of  figures  for  1899  and  1909.  An 
average  of  five  persons  to  a  farm  is  considered  fairly  re- 
liable, and  each  person  is  assumed  to  eat  about  5  bushels  of 
potatoes  a  year.^  From  these  figures  we  can  estimate  the 
number  of  bushels  eaten  on  farms.  We  have  then  figures 
from  which  we  can  compute,  rather  roughl}',  the  number  of 
bushels  to  be  handled  annually  on  the  potato  markets  of 
the  United  States. 

From  the  above  table,  we  see  that  nearly  one-seventh  of 
the  potato  crop  has  to  be  saved  for  next  year.  About  one- 
twenty-fourth  of  the  whole  crop,  or  one-twelfth  of  the 
quantity  stored,  is  lost  through  shrinkage  and  rotting. 
Starch  manufacture  and  home  consumption  of  potatoes 
on  the  farm  also  take  some  of  the  crop.  The  quantity 
left,  after  subtracting  all  of  these  from  the  crop,  repre- 
sents, in  a  rough  way,  the  number  of  bushels  of  American- 
grown  potatoes  to  be  handled  on  the  market.  If  we 
then  balance  the  imports  and  exports,  and  add  the  excess 
of  imports  to  this  figure,  we  have  the  total  number  of 
bushels  of  potatoes  handled  in  the  American  markets. 
This  is  approximately  184,930,000  bushels,  or  30,822  cars.^ 

According  to  statistics  published  by  the  United  States 
Department  of  Agriculture,  about  50  per  cent  of  the 
potato  crop  has  been  sold  by  January  first.  A  relatively 
large  proportion  of  this  quantity  is  sold  by  farmers  at 
the  time  of  digging,  or  shortly  afterward.  The  following 
table  ^  gives  figures  for  the  total  of  19  Northern  states  :  — 


1  The  average  annual  consumption  per  capita  in  the  United  States  is  3.5 
bushels.  The  consumption  is  higher  than  this  in  the  North  and  lower 
in  the  South,  where  sweet  potatoes  are  eaten  in  place  of  Irish  potatoes. 
Funk,  in  Farmers'  Bui.  635,  finds  an  average  farm  consumption  (483 
farms)  of  5.7  bushels. 

2  Car  of  600  bushels. 

»  Monthly  Crop  Report,  January  31,  1916,  p.  8. 


Markets,  Marketing  and  Storage 


239 


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240 


The  Poiaio 


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Markets,  Marketing  and  Storage  241 

It  will  be  seen  that  there  is  an  average  difference  in  price 
for  a  bushel  on  December  1st  and  March  1st  of  only  3 
cents.  The  question  which  then  suggests  itself  is  "Does 
it  pay  the  farmer  to  store  potatoes  over  winter  ?  " 

When  we  compare  the  prices  obtained  for  a  bushel  on 
December  1st  and  March  1st,  it  would  seem  that  the 
farmer  loses  money  by  storing  his  potatoes.  Surely  the 
difference  of  3  cents  a  bushel  does  not  begin  to  cover  the 
extra  cost  of  storage  nor  the  extra  shrinkage  and  loss 
through  rotting.  Wliy  not  sell  all  the  potatoes  at  digging 
time,  or  at  least  before  January  1st?  There  are  several 
very  good  reasons  for  this. 

In  the  first  place,  it  would  be  very  difficult  for  the  dealers 
to  handle  the  whole  crop  of  potatoes  in  the  fall.  They 
lack  the  warehouse  room  and  the  help  to  take  care  of  all 
the  crop  at  one  time.  Dealers  would  be  swamped  with 
potatoes  for  a  short  time,  and  then  have  no  more  to  handle 
for  a  long  time.  Secondly,  there  is  a  shortage  of  rail- 
road cars  in  the  fall,  and  it  would  be  impossible  to  ship  the 
whole  crop  at  one  time.  Then,  too,  the  farmer  is  pressed 
for  time  in  the  fall  and  can  use  his  teams  to  better  advan- 
tage than  in  hauling  potatoes.  He  can  better  afford  to 
cart  potatoes  in  the  winter,  when  there  is  less  to  be  done. 

Probably  the  principal  reason  for  not  selling  the  whole 
crop  in  the  fall  is  the  automatic  lowering  of  prices  which 
follows  an  attempt  to  market  too  many  potatoes  at  that 
time.  The  dealers  in  potatoes  will  take  only  so  many 
bushels  in  the  fall,  and  any  sold  above  this  quantity  are 
sold  at  a  constantly  decreasing  figure.  By  storing  part 
of  his  crop,  the  farmer  equalizes  the  distributing  of  it  on 
the  market  and  gets  a  better  net  return  than  he  would 
by  selling  all  shortly  after  digging. 

If  prices  hold  up  in  the  fall,  it  will  probably  be  better 


242 


The  Potato 


for  the  farmer  to  market  the  larger  part  of  his  crop  at  once 
than  for  him  to  store  it.  Occasionally,  however,  the  stor- 
age of  potatoes  becomes  very  profitable. 

In  1914,  with  a  crop  of  over  400,000,000  bushels,  the 
price  of  potatoes  dropped  during  the  winter.  In  1915, 
when  w^eather  conditions  were  unfavorable,  and  the  crop 
suffered  badly  in  storage,  prices  went  up  rapidly  during 
the  winter.  The  winter  of  1915-1916  was  one  in  which 
stored  potatoes  of  good  quality  brought  a  high  price.  The 
following  table  of  estimated  values  a  bushel,  taken  from 
the  United  States  Government  Monthly  Crop  Reports, 
shows  the  range  in  price  a  bushel  during  the  seasons  men- 
tioned : 

.Table  XVII 


Crop  Reports  op 


Estimated  Farm  Values 


June 
August 
September 
October 
November 
January- 
March   . 
April 


50.8 

71.3 

56.3 

87.1 

50.3 

74.9 

48.8 

64.7 

60.8 

52.8 

70.6 

49.7 

94.4 

50.4 

97.6 

47.8 

Marketing  the  crop 

The  methods  of  marketing  the  potato  crop  may  be 
simple,  or  they  may  become  complicated,  requiring  several 
handlings  and  the  services  of  a  number  of  persons. 

Probably  the  simplest  method  of  marketing  the  crop  is 
for  the  farmer  to  sell  directly  to  the  consumer,  either  haul- 


Markets,  Marketing  and  Storage  243 

ing  the  potatoes  by  wagon  or  shipping  them.  This  can 
only  be  done  when  the  farmer  Hves  fairly  close  to  market 
and  where  he  has  good  storage  facilities,  so  that  he  can 
sell  small  quantities  at  a  time.  Such  a  method  of  market- 
ing is  usually  highly  satisfactory,  for  it  gives  the  pro- 
ducer the  highest  possible  share  of  the  profits  and  the 
consumer  the  lowest  retail  price.  The  farmer  may  also 
sell  locally  to  retail  grocers,  thus  eliminating  the  services 
of  one  to  three  or  four  middlemen.  Obviously,  only  a 
very  small  proportion  of  the  total  crop  can  be  marketed 
in  these  ways.  Such  methods  of  marketing  necessitate 
much  labor,  and  require  good  storage  accommodations 
and  an  intimate  knowledge  of  markets. 

Marketing  through  local  dealers 

It  is  usually  necessary  for  the  farmer  to  sell  his  potatoes 
to  a  local  dealer,  who  in  turn  stores  some  of  them  and  sends 
the  remainder  to  the  commission  men  in  the  larger  cities. 
These  dealers  are  familiar  with  the  requirements  of  the 
different  markets  and  are  usually  able  to  sell  the  potatoes 
to  a  better  advantage  than  can  the  farmer. 

The  local  dealers  or  buyers  are  to  be  found  in  nearly 
all  towns  where  large  quantities  of  potatoes  are  being 
brought  in  by  the  farmers.  They  usually  sort  and  bag  the 
potatoes  and  load  them  in  cars  for  shipping.  Occasionally 
a  farmer  or  a  small  group  of  farmers  will  load  and  ship  a 
car,  but  the  bulk  of  the  crop  is  handled  by  local  buyers. 
These  buyers,  according  to  Taylor,  may  be  of  several  sorts. 
They  may  be  agents  of  large  potato  companies  in  the  cities, 
or  they  many  be  independent  buyers  who  combine  other 
lines  of  business  with  that  of  potato-buying,  or  they  may 
be  agents  of  farmers'  warehouses  or  cooperative  associa- 


244  The  Potato 

tions.  The  large  potato  companies  usually  have  from  one 
to  several  buyers  in  the  more  important  potato-growing 
sections,  to  purchase  from  the  farmers  and  ship  the  pota- 
toes, at  their  direction,  to  the  best  markets.  These  buyers 
handle  potatoes  at  4  to  8  cents  a  bushel.  The  agents  of 
the  farmers'  warehouses,  who  are  dealing  in  other  prod- 
uce as  well  and  have  lower  running  expenses,  are  able  to 
handle  a  bushel  for  about  3  cents. 

In  many  of  the  large  cities  there  are  companies  which 
handle  only  potatoes.  These  companies  get  potatoes 
from  the  farmers  through  the  local  buyers,  and  then 
by  means  of  telegraph  and  telephone  ascertain  the 
best  markets  and  direct  the  shipment  of  the  cars  to 
them.  They  are  handling  great  quantities  of  potatoes 
and  can  afford  to  spend  large  sums  in  order  to  get  their 
goods  to  the  best  market.  Companies  of  this  sort 
often  pay  telephone  charges  of  over  one  thousand 
dollars  a  month. 

Where  farmers  can  be  persuaded  to  cooperate  and  to 
place  faith  in  the  organization  and  in  its  agents,  the  co- 
operative method  of  selling  potatoes  has  proved  very  satis- 
factory. Such  organizations  have  agents  in  the  small 
towns  near  which  the  members  live.  These  agents  receive 
potatoes  from  the  farmers,  and  ship  them  at  the  direction 
of  the  manager  of  the  company.  These  managers  have  to 
compete  with  the  large  potato  companies,  and  are  often 
at  a  disadvantage  in  getting  information  as  to  markets. 
Farmers'  companies  should  either  be  in  touch  with  large 
distributors  or  arrange  with  some  company  for  "buying 
information." 

Local  dealers  usually  find  it  necessary  to  sort  and  clean 
the  potatoes  brought  to  them,  since  growers  seldom 
make  a  practice  of  sorting  carefully.    Potatoes  are  sorted, 


Markets,  Marketing  and  Storage  245 

bagged  or  put  in  barrels  for  shipment.  Occasionally  a 
farmer  will  insist  that  his  potatoes  be  sold  without  being 
sorted  before  shipment.  These  are  sorted  in  the  city 
and  the  culls  are  thrown  out.  The  grower  gets  nothing 
for  the  culls  and  he  must  pay  the  expense  of  freight  on 
them. 

Grading 

Potatoes  are  poorly  graded,  and  for  this  reason  the  cost 
of  marketing  is  higher  than  in  the  case  of  goods  which  are 
classified  by  grades.  Potatoes  of  several  varieties  are  usu- 
ally raised  in  the  same  section,  and  it  is  often  hard  to  fill  a 
car  with  only  one  variety.  Experienced  potato-shippers 
sort  and  grade  carefully  and  get  a  higher  price  a  bushel 
than  is  ordinarily  paid.  One  produce  exchange  in  Vir- 
ginia has  so  standardized  its  potatoes  that  wholesalers 
order  by  wire,  without  seeing  the  goods.  Sorting  and  grad- 
ing on  the  farm,  or  at  least  before  loading  on  the  cars,  not 
only  makes  it  possible  to  secure  a  higher  price  for  the  pota- 
toes, but  reduces  the  cost  of  marketing  as  well.  The 
farmer  ultimately  pays  the  cost  of  grading,  and  often  after 
he  has  paid  the  freight  on  as  much  as  a  ton  of  dirt  and 
culls. 

Packages 

Early  potatoes  are  usually  shipped  in  three-bushel 
barrels,  covered  with  canvas,  or  in  bushel  boxes.  The 
barrels,  with  covers,  cost  about  20  cents  apiece.  Bushel 
boxes  —  13  X  16  X  13  inches  deep  —  cost  about  $30 
a  hundred.  Seed  potatoes  are  frequently  shipped  in 
double-headed  barrels  of  165  pounds  capacity.  These 
cost  about  30  cents  each. 


246  The  Potato 

Late  potatoes  are  usually  shipped  in  burlap  sacks, 
holding  two  bushels.  Sometimes  flour  barrels  are  used, 
and  occasionally  the  potatoes  are  shipped  in  bulk  in  car- 
load lots. 

Shi'p'ping 

When  potatoes  are  shipped  in  bulk,  it  is  necessary  to 
line  the  whole  car  with  lumber.  If  the  potatoes  are 
bagged,  it  is  not  necessary  to  line  the  car,  but  a  false  floor 
must  be  put  in.  It  costs  the  local  dealer  ordinarily  a 
little  over  $30  to  line  a  car. 

In  the  winter,  it  is  necessary  to  heat  the  cars,  and  a  man 
has  to  be  sent  along  with  the  car  to  regulate  the  heat. 
Here  again  the  larger  dealer  has  the  advantage,  since  he 
can  ship  several  cars  at  once  and  reduce  the  cost  of  heating. 

Water  transportation  plays  an  important  part  in  the 
shipment  of  early  potatoes  from  the  southern  states  to 
the  larger  cities  of  the  North. 

Most  of  our  potatoes  are  raised  near  the  larger  towns  and 
cities,  and  the  distances  of  shipment  are  relatively  small, 
Chicago  receives  potatoes  from  Michigan,  Illinois,  and 
Wisconsin,  a  large  part  of  her  supply  coming  from  the  last 
state  mentioned.  New  York  and  Philadelphia  get  pota- 
toes from  New  York  state,  New  England,  Long  Island, 
New  Jersey  and  the  southern  Atlantic  states.  Only  a 
few  states  raise  potatoes  for  interstate  shipment.  Taylor 
says  that  three-fourths  of  the  potatoes  grown  are  consumed 
in  the  states  which  raised  them.  Maine  raises  25  per  cent 
of  the  potatoes  for  interstate  shipment,  Michigan  24  per 
cent,  Wisconsin  20  per  cent,  Minnesota  16  per  cent  and 
Colorado  8  per  cent. 

After  reaching  the  city  in  which  they  are  to  be  marketed, 
the  potatoes  may  take  any  one  of  several  courses  to  the 


Markets,  Marketing  and  Storage  247 

consumer.  Very  often  they  pass  through  the  hands  of  a 
commission  man,  and  frequently  they  go  directly  to  the 
wholesaler.  In  the  larger  cities,  a  considerable  part  of 
the  crop  goes  to  the  commission  man,  who,  in  turn,  dis- 
tributes it  among  the  jobbers  or  wholesalers.  The  com- 
mission man  may  employ  a  number  of  salesmen,  or  he  may 
depend  upon  an  expert  potato  broker  to  bring  in  orders 
from  the  wholesalers.  Often  goods  are  shipped  around 
the  commission  men  to  the  brokers,  and  thence  to  the 
wholesalers. 

The  diagram  (Fig.  18)  may  help  to  make  clear  the 
methods  of  marketing  potatoes.  Perhaps  it  will  seem  that 
there  are  too  many  middlemen  concerned  in  the  market- 
ing of  this  crop.  In  many  cases  there  are.  We  must  not 
lose  sight  of  certain  conditions  of  potato  marketing,  how- 
ever. The  retailer  sells  in  small  quantities,  and  he  has  no 
room  to  store  more  than  a  small  supply  of  potatoes.  He 
must  needs  depend  upon  the  wholesaler  for  his  supply. 
The  wholesaler  in  turn  has  to  cater  to  a  fairly  definite  de- 
mand from  the  retailer.  He  cannot  take  ever^^-thing  which 
is  sent  to  him  by  the  farmer,  but  must  have  access  to  the 
supplies  of  the  commission  man  in  order  to  get  the  desired 
variety  and  grade.  So  we  have  the  potatoes  coming  to  the 
large  dealer  or  commission  man,  who  sells  in  small  lots  to 
the  wholesalers,  and  the  wholesalers  divide  the  product 
into  still  smaller  parcels  and  sell  to  the  retailer.  The 
lack  of  proper  grading,  the  bulkiness  of  the  goods,  and  the 
demand  for  small  quantities  at  a  time,  tend  to  make 
necessary  the  services  of  several  classes  of  dealers  in  the 
process  of  marketing  potatoes. 

There  is  no  chance  to  gamble  on  potatoes,  as  on  wheat 
and  certain  other  crops,  since  there  are  no  exchanges  where 
the  traders  can  come  together.     The  potato  market  is 


248 


The  Potato 


lO 


Fig.  18.  Diagram  illustrating  interrelationships  of  producer,  middle- 
men and  consumer  of  potatoes.  1.  Farmer.  2.  Agent  of  farmer.s'  ware- 
house or  of  cooperative  company.  3.  Independent  local  buyer.  4.  Local 
buyer  for  large  potato  company.  5.  Wholesaler.  6.  Commission  man. 
7.  Broker.     8  and  9.  Retailer.     10.  Consumer. 


Markets,  Marketing  and  Storage  249 

not  very  highly  organized,  and  exact  market  information 
is  very  difficult  to  obtain. 

Early  and  late  potatoes 

The  earliest  potatoes  to  reach  the  northern  markets 
come  from  the  Bermudas  and  Texas  in  January  and 
February.  Florida  and  other  southern  states  add  to  the 
supply  a  little  later,  and  about  the  first  of  June  a  large 
quantity  begins  to  come  in  from  Virginia  and  other  south 
central  states. 

Early  potatoes  from  southern  New  Jersey  enter  the 
market  about  July  twentieth  and  those  from  the  northern 
part  of  the  state  and  from  Long  Island  about  ten  days  to 
two  weeks  later.  Early  potatoes  from  New  York  and 
Maine  are  usually  marketed  between  the  first  and  fifteenth 
of  September.  The  southern  potatoes  have  little  effect 
upon  the  price  paid  for  northern-grown  potatoes,  providing 
they  are  out  of  the  market  by  August.  If  southern  pota- 
toes are  late  in  reaching  the  northern  markets,  potatoes  from 
New  Jersey,  Long  Island  and  Pennsylvania  are  sold  in  com- 
petition with  them  and  consequently  bring  a  lower  price. 

The  main  crop  of  late  potatoes  begins  to  come  into  the 
market  early  in  October.  From  then  on,  the  extent  of 
the  sales  and  the  price  for  a  bushel  depend  upon  many 
factors.  Chief  among  these  is  the  supply  of  potatoes  then 
upon  the  market. 

Markets 

The  larger  potato  markets  of  the  United  States  are  New 
York,  Chicago,  Minneapolis,  St.  Louis,  Cincinnati,  Den- 
ver, San  Francisco  and  Boston.  Chicago  handles  annually 
about  24,000  cars,  or  over  60  cars  a  day.     Each  of  these 


250  The  Potato 

cities  draws  upon  several  states  for  its  supply  of  potatoes. 
The  eastern  cities  often  get  European  potatoes  in  years  of  a 
poor  crop,  and  occasionally  these  potatoes  get  as  far  west 
as  Chicago. 

Range  and  'prices 

There  are  few  crops  which  fluctuate  as  much  in  value 
as  the  potato.  In  a  single  season  the  prices  may  show  a 
range  of  as  much  as  70  or  80  cents  a  bushel.  The  highest 
prices  are  usually  obtained  in  the  late  winter  and  early 
spring  just  as  the  early  potatoes  come  on  to  the  market. 
This  value  is  not  likely  to  fluctuate  a  great  deal  while 
early  potatoes  are  abundant,  but  it  drops  off  rather  sud- 
denly as  soon  as  the  late  crop  comes  in.  Usually  the  price 
for  a  bushel  remains  fairly  constant  through  the  winter, 
though  it  may  fluctuate  a  little  either  way.  Later  in  the 
winter  it  is  likely  to  rise  somewhat  or  to  drop  off  slightly. 
These  fluctuations  in  price  are  due  largely  to  a  change  in 
the  relation  of  supply  to  demand. 

In  1899,  the  farm  price  was  as  low  as  22  cents  in  Iowa 
and  as  high  as  $1.10  in  Arizona,  with  an  average  price  the 
country  over  of  36  cents.  In  1915,  the  prices  ranged  from 
35  cents  in  South  Dakota  to  $1.15  in  Florida,  with  an  aver- 
age of  61.6  cents.  These  Avide  fluctuations  in  price  illus- 
trate the  effect  of  supply  and  demand  upon  the  value  a 
bushel.  The  average  farm  price  a  bushel  for  the  years 
1906-1910  was  60.4  cents.  The  highest  average  farm 
price  on  December  first,  since  1866,  was  79.9  cents  in  1911, 
and  the  lowest  in  the  same  period  was  26.6  cents  in  1895. 
In  recent  years,  Arizona  has  had  the  highest  value  to  the 
acre,  averaging  $127.68  for  the  5  years  from  1910-1914. 
The  lowest  value  to  the  acre  during  the  same  period  was 
$42.43  in  Missouri. 


Markets,  Marketing  and  Storage 


251 


The  following  table  ^  gives  the  prices  received  for  a 
bushel  by  the  Burlington  County  Farmers'  Exchange  of 
New  Jersey,  for  four  years  : 


Table  XVIII. 


Seasonal  Variation  in  Farm  Price  for  a 
Bushel 


Period 

1911 

1912 

1913 

1914 

July    12         .     . 

$1.25-11.35 

July    15-20        . 

1.25-    1.30 

|.65-$.80 

S.60-$.80 

July   25-30 

1.05-   1.20 

.68-  .83 

.65-  .68 

$.60-1.80 

Aug.     1-10        . 

1.05-    1.25 

.62-  .80 

.65-  .73 

.53-  .70 

Aug.  20-31 

.80-   1.00 

.55-  .60 

.60-  .68 

.50-  .58 

Sept.    1-15 

.48-  .50 

.60-  .68 

.52-  .55 

Sept.  15-21        . 

.75-  .80 

A  survey  of  the  figures  published  by  the  United  States 
Department  of  Agriculture  shows  that  the  price  paid  for  a 
bushel  on  December  1st  tends  to  vary  immensely  with  the 
size  of  the  crop  : 

Table  XIX 


Year 

Production 

Farm  Pi^ice  —  in  Cents 

(000  omitted) 

December   1st 

1904 

332,830 

45.3 

1905 

260,740 

61.7 

1906 

308,040 

51.1 

1907 

298,260 

61.8 

1908 

278,990 

70.6 

1909 

289,190 

54.1 

1910 

349,030 

55.7 

1911 

292,740 

79.9 

1912 

420,650 

50.5 

1913 

331,530 

68.7 

1914 

405,920 

48.9 

1  N.  J.  Extension  Bui.,  Vol.  5,  1915. 


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Fig.  19.  Average  yields  of  potatoes  to  the  acre,  a,  50  bushels ;  h, 
60  bushels  ;  c,  70  bushels ;  d,  80  bushels  ;  c,  90  bushels ;  /,  100  bushels ; 
0,  110  bushels. 

252 


Markets,  Marketing  and  Storage  253 

The  graph  in  Figs.  19  and  20  illustrates  this  same  rela- 
tion between  production  to  the  acre  and  value  a  bushel. 

If  the  consumer  of  potatoes  examines  a  list  of  farm  prices, 
as  published  by  the  United  States  Department  of  Agricul- 
ture, he  is  usually  surprised  to  find  that  he  is  paying  at 
least  double  what  is  paid  the  farmer  for  a  bushel  of  potatoes. 

Under  present  conditions  the  cost  of  marketing  potatoes 
is  relatively  high.  It  could  be  cut  down  appreciably  if 
farmers  would  codperate  in  marketing  and  would  grade 
their  stock  carefully.  Taylor  publishes  statements  from 
a  potato  merchant  to  show  the  distribution  of  the  cost  of 
marketing  a  bushel. 

The  local  buyer  pays,  on  the  average,  three  cents  a 
bushel  for  the  labor  of  handling  the  potatoes.  Bags  cost 
about  5  cents,  and  the  dealer  asks  a  profit  of  about  2 
cents  a  bushel. 

The  freight  charges  vary  a  great  deal  with  the  distance 
of  shipment.  Taylor  says  that  it  costs  about  8  to  8i 
cents  a  bushel  to  ship  from  Wisconsin  to  Chicago.  To 
the  freight  must  be  added  the  cost  of  lining  and  firing  the 
car,  when  the  potatoes  are  shipped  in  the  winter.  This 
will  cost  about  2  cents  a  bushel.  It  costs  the  small 
shipper  from  $7  to  $10  a  car  for  heating,  while  the  large 
dealer  will  send  through  a  string  of  5  to  20  cars  for  about 
$1.50  each.  We  must  count  on  a  certain  loss  in  transit 
through  frosting  and  rotting.  Then,  too,  under  present 
methods  of  grading  and  marketing  there  is  almost  always 
a  loss  of  20  to  40  bushels  of  culls  to  a  car,  and  occasionally 
as  high  as  100  to  150  bushels.  These  potatoes  are  a  total 
loss  to  the  buyer,  and  the  freight  paid  on  them  is  also  lost. 
As  a  result  of  this  loss  on  culls,  the  price  for  a  bushel  rises 
somewhat. 

The  larger  distributor  or  commission  man  usually  nets 


254 


The  Potato 








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Fig.  20.     Average  prices  of  potatoes  by  the  bushel,     a,  30  cents ;  h, 
40  cents ;  c,  50  cents ;  d,  60  cents ;  e,  70  cents ;   /,  80  cents ;  g,  90  cents. 


Marhets,  Marketing  and  Storage  255 

about  2  cents  a  bushel  profit  in  addition  to  his  expenses 
of  li  to  2  cents  a  bushel. 

The  wholesale  dealer  incurs  an  expense  of  5  to  7  cents  a 
bushel  in  draying  to  his  warehouse  and  later  distributing 
to  the  retailer.  He  must  also  make  a  profit  on  each  bushel 
handled. 

There  is  also  the  retailer,  whose  profit  must  necessarily 
be  high.     This  last  profit  varies  from  15  to  30  cents. 

A  summary  of  all  expenses  incidental  to  marketing  the 
crop  shows  a  cost  of  39  to  70  cents  a  bushel : 

Table  XX 

Retailer 15-30  cents 

Wholesaler 5-10  cents 

Transportation 8-10  cents 

Larger  distributor 3-4  cents 

Burlap  sacks  and  car  linings 3-5  cents 

Local  dealer 5-11  cents 

39-70  cents 

The  cost  of  marketing  varies  greatly,  depending  on  a 
number  of  factors.  The  distance  to  market  affects  freight 
charges  very  directly.  The  time  of  year  when  the  potatoes 
are  shipped  has  a  bearing  on  loss  in  transit  and  cost  of  heat- 
ing the  cars.  Costs  are  markedly  influenced  also  by  the 
number  of  middlemen  helping  in  the  sale  of  the  potatoes. 
Each  one  must  make  a  profit.  There  is  a  lack  of  definite 
standards  of  quality  in  potatoes,  and  consequently  at 
each  exchange  of  goods  there  is  keen  bargaining  to  buy 
low  and  sell  high.  The  retailers'  cost  of  marketing  de- 
pends largely  upon  the  quantities  purchased  at  one  time 
by  the  consumer,  and  the  cost  of  delivering  and  of  main- 
tenance. 

It  is  obvious  that  a  lowering  of  the  cost  of  marketing  will 
be  profitable  both  to  the  producer  and  the  consumer.     The 


256  The  Potato 

latter  will  be  able  to  buy  potatoes  for  less  a  bushel,  and  the 
former  will  receive  a  larger  share  of  the  retail  price  than 
before.  The  farmer  should  aim  to  cut  down  the  expense 
of  growing  and  hauling  to  the  local  buyer.  He  can  lower 
freight  charges  by  sorting  carefully  and  thereby  not  pay- 
ing freight  on  culls.  By  grading  his  stock  and  market- 
ing the  best,  he  can  raise  the  price  which  he  receives  a 
bushel.  Perhaps  the  most  effective  means  of  lowering  the 
cost  of  marketing  is  for  the  farmers  to  organize  coopera- 
tive selling  companies.  Such  organizations  have  most 
of  the  advantages  of  the  larger  potato  companies,  in  the 
way  of  decreased  cost  of  hauling  and  better  marketing 
information.  In  some  cases  the  number  of  middlemen 
can  be  cut  down.  We  must  remember,  however,  that  the 
potato  is  a  bulky  crop  of  a  perishable  nature  and  therefore 
must  be  carefully  held  in  storage  while  awaiting  shipment. 
This  necessitates,  for  part  of  the  crop  at  least,  the  services 
of  the  large  distributor  who  can  hold  the  goods  safely 
until  called  for  by  the  wholesalers.  There  must  be  re- 
tailers who  can  sell  potatoes  in  small  lots  to  the  consumer. 
Perhaps  one  or  even  two  of  these  steps  might  be  dropped 
out  occasionally,  and  the  expense  of  handling  several  times 
be  eliminated. 

There  are  many  factors  which  determine  the  price  of 
potatoes.  A  careful  study  of  these  and  skill  in  forecast- 
ing as  accurately  as  possible  the  probable  price  which 
potatoes  will  bring  from  the  time  they  are  stored  until  the 
last  of  them  are  sold  late  in  the  spring  will  determine 
whether  it  will  pay  to  store  them  or  not. 

The  farm  price  of  potatoes  at  digging  time  is  usually 
very  low.  Most  growers  do  not  have  storage  facilities 
and  must  put  their  product  on  the  market  in  the  fall. 
This  increases  the  supply  and  lowers  the  price. 


Markets,  Marketing  and  Storage  257 

The  principal  factor  which  will  determine  the  advisa- 
bility of  storage  is  the  probable  winter  and  spring  price ; 
others  are  the  soundness  of  the  tubers  at  digging  time ; 
relative  ease  of  getting  them  on  the  market  in  the  winter  ; 
their  use  for  table  stock  or  seed  purposes  and  so  forth. 

Ordinarily  a  low-price  season,  resulting  from  overpro- 
duction, will  be  followed  by  a  season  of  high  prices.  The 
grower  should  be  carefully  informed  concerning  the 
acreage  of  the  whole  county  during  the  growing  season  and 
the  reported  condition  of  the  crop  from  different  sections. 
An  extensive  acreage  and  a  favorable  season  results  in 
low  prices. 

The  average  consumption  per  capita  in  the  United 
States  is  from  3§  to  4  bushels.  If  the  acreage  and  weather 
conditions  over  the  whole  country  are  likely  to  produce 
a  crop  of  over  400  million  bushels,  low  prices  may  be 
looked  for.  The  population  of  the  United  States  is  ap- 
proximately 100  millions.  At  the  rate  of  consumption  of 
3|  bushels  for  each  person,  the  total  consumption  will  be 
350  million  bushels. 

The  United  States  Department  of  Agriculture  issues  a 
crop  reporter  each  month  which  gives  the  condition  of  the 
potato  and  other  crops  from  all  over  the  country.  It  is 
issued  free  to  all  and  arrives  about  the  20th  of  each  month. 

The  amount  of  importation  of  potatoes  into  the  United 
States  is  regulated  by  the  price  here  and  elsewhere,  which  is 
in  turn  largely  determined  by  the  quantity  of  production. 
The  protective  tariff  on  potatoes  is  10  cents  a  bushel. 

The  basis  for  storage  must  take  into  account  American 
production  and  the  probable  price  and  the  foreign  pro- 
duction and  price.  When  home  prices  reach  a  high  level, 
foreign  potatoes  are  sure  to  become  a  price-determining 
factor. 


258 


The  Potato 


It  is  obvious  that  all  seed  stock  must  be  stored  either 
by  the  grower,  who  may  save  his  own  seed,  or  by  some  large 
concern,  who  may  store  it  for  sale  to  growers  in  the  spring 
(see  Fig.  21).  Seed  stock  should,  perhaps,  be  stored  more 
carefully  than  potatoes  for  eating  purposes.  Complete 
dormancy  is  necessary  if  the  seed  is  to  produce  a  good 
crop.     If  storage  is  not  carried  out  properly,  the  tubers 


Fig.  21.     Potato  storage  house. 

become  shriveled  and  are  likely  to  produce  long,  weak 
sprouts,  which  greatly  weakens  them.  Many  growers 
follow  the  practice  of  storing  stock  in  bags  and  turning 
the  bags  every  week  in  the  spring  to  break  off  the  sprouts 
and  prevent  rapid  deterioration.  This  practice  when  fea- 
sible seems  to  be  very  successful. 


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CHAPTER  XIV 
USES  OF   THE  POTATO 

The  potato  is  one  of  the  most  important  vegetable 
foods.  Its  rise  in  popularity  since  its  introduction  into 
Europe  has  been  very  rapid.  At  first  the  tubers  were 
regarded  as  poisonous,  and  only  a  few  of  the  more  ven- 
turesome dared  to  eat  them.  When  these  men  found  the 
potato  to  be  edible,  the  people  of  France  and  Germany 
began  to  plant  it  as  a  reserve  food  in  case  other  crops 
failed.  By  1770  it  had  become  a  common  field  crop  in 
Europe.  These  potatoes,  however,  were  usually  small 
in  size  and  of  poor  quality,  and  for  this  reason  they  were 
used  principally  as  a  food  for  animals.  The  possibilities 
of  improving  the  crop  were  soon  learned,  and  by  1840  it 
was  being  widely  used  as  a  substitute  for  the  cereals  and 
other  starchy  foods.  In  1900  it  was  estimated  that  the 
potato  furnishes  about  ^  of  the  total  food  consumed  in 
the  United  States. 

Although  it  is  primarily  a  food  crop,  the  potato  has  a 
great  variety  of  uses  (see  Plate  XVI).  For  a  long  time  it 
was  the  chief  source  of  commercial  starch,  and  although 
cornstarch  is  now  preferred,  the  starch  of  the  potato 
is  still  used  in  large  quantities  to  make  sizing  for  paper 
and  textiles.  Another  important  use  for  potatoes  is  in 
the  manufacture  of  industrial  alcohol.  This  industry  is 
almost  unknown  in  this  country,  but  in  Europe  it  has 
259 


260 


The  Potato 


attained  large  proportions.  Potato  flour,  glucose,  sirup, 
mucilage  and  a  number  of  tinctures  are  also  made  from 
potatoes.  In  Europe  the  small  potatoes  and  culls  are 
used  to  feed  stock,  and  the  slops  from  the  manufacture 
of  alcohol  are  carted  away  daily  for  this  purpose. 


USE   FOR  HUMAN   FOOD 

So  accustomed  have  we  become  to  the  potato  that  it 
is  difficult  to  imagine  our  tables  without  it.  It  furnishes 
us  daily  with  an  abundant  supply  of  nutrients  at  a  rela- 
tively low  price.  Primarily  it  is  a  starchy  food,  but  it 
also  contains  some  protein  and  a  little  mineral  matter, 

and  it  adds  bulk 
to  the  food  eaten. 
It  is  said  that  the 
potato  represents 
3.9  per  cent  of  the 
total  cost  of  food, 
and    furnishes    5.3 

Fig.  22.  Composition  of  the  potato,  a,  fat;  per  CCUt  of  the  heat 
?,  crude  fiber  and  other  carbohydrates  exclusive  ^^lories  needed  by 
of  starch ;    c,  protein  ;   a,  ash.  •' 

the  body.  As  the 
potato  is  somewhat  deficient  in  protein  and  fats,  it  cannot 
be  used  exclusively  in  the  diet,  but  must  be  combined 
with  lean  meat,  legumes,  eggs  or  other  protein-supplying 
foods,  and  with  cream,  butter  or  other  fatty  substances. 
Not  only  does  the  potato  furnish  considerable  nutri- 
ment, but  it  supplies  it  in  an  easily  digestible  form.  The 
starch  in  potatoes  is  much  more  readily  digested  than 
the  starch  of  cereals  or  other  starch-producing  foods.  In 
Germany  a  gruel  made  from  the  pulp  of  baked  potatoes 
is  used  to  feed  infants  and  invalids. 


Uses  of  the  Potato  261 

It  is  said  that  about  20  per  cent  of  the  tuber  is  waste. 
As  this  percentage  is  mostly  skin  and  that  part  of  the 
cortical  layer  removed  with  it,  the  percentage  will  vary 
with  the  size  of  the  potato,  the  shape  and  the  care  used 
in  feeding  it.  About  62  per  cent  of  the  whole  tuber  is 
water,  and  about  78  per  cent  of  the  edible  portion  is 
water.  Carbohydrates  form  about  18  per  cent  of  the 
peeled  tuber.  About  2  per  cent  is  protein  and  1  per  cent 
ash.  The  fat  content  is  rather  low,  being  only  0.1  per 
cent  (see  Fig.  22).  A  large  proportion  of  the  protein 
and  minerals  is  contained  in  the  outer  layers  of  the  potato, 
and  frequently  much  of  this  is  lost  in  careless  peeling. 

Quality  lohen  cooked 

The  requirements  for  quality  in  a  cooked  potato  vary, 
depending  on  the  personal  taste  of  the  user  and  on  the 
particular  way  in  which  the  tubers  are  to  be  cooked.  In 
America  a  mealy,  white-centered  potato  is  usually  pre- 
ferred for  boiling,  steaming  and  baking.  Europeans  fre- 
quently prefer  a  less  starchy  potato,  which  means  one 
with  a  higher  percentage  of  protein.  Such  potatoes  are 
richer  in  flavor  and  of  better  substance  than  the  mealy 
ones.  In  some  sections  of  Europe  a  mealy  potato  is  in 
demand  for  boiling,  and  a  waxy  potato  for  frying  and  for 
salads.  If  Americans  were  to  discriminate  in  favor  of  cer- 
tain textures  of  flesh  for  special  purposes,  varieties  meet- 
ing the  requirements  would  undoubtedly  be  developed. 

There  are  many  factors  influencing  the  quality  of  a 
potato  when  cooked  and  its  value  as  a  food.  Undoubtedly 
the  nature  of  the  soil  in  which  the  tubers  are  formed  has 
some  effect  upon  these  characters,  but,  so  far,  no  definite 
relation  has  been  worked  out.     It  is  also  true  that  disease 


262 


The  Potato 


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Uses  of  the  Potato  •  263 

and  seasonal  conditions  affect  quality.  In  addition  to 
these  factors,  there  are  chemical  composition,  degree  of 
maturity,  conditions  of  storage  and  methods  of  prepara- 
tion for  the  table,  all  having  an  important  bearing  on 
quality  and  food  value. 

There  are  three  textures  of  flesh  in  the  cooked  potato 
as  determined  by  the  chemical  composition :  soggy, 
waxy  and  mealy.  The  soggy  potato  is  usually  rather 
low  in  starch  and  relatively  high  in  protein.  In  potatoes 
of  this  type,  when  the  starch  grains  are  heated  they  swell 
up,  but  there  are  not  enough  of  them  to  burst  the  cell- 
walls  in  the  tuber  and  give  the  starchy  and  mealy  condi- 
tion so  often  desired.  The  tuber  more  easily  absorbs 
water  and  becomes  wet  and  soggy  at  the  center.  The 
protein  also  tends  to  coagulate  and  make  the  flesh  heavier 
than  it  is  in  the  mealy  potato. 

In  potatoes  of  a  waxy  texture,  there  is  a  greater  propor- 
tion of  starch  to  protein.  The  protein  serves  as  a  frame- 
work which  prevents  the  starch  from  forming  flaky  masses 
and  holds  the  potato  together  better.  Such  potatoes  are 
desired  for  salads  and  for  garnisliing  meat  dishes. 

In  the  mealy  potato,  the  cells  are  packed  with  starch 
grains.  These  expand  with  the  heat  of  cooking  and  tear 
apart  the  cell-walls,  making  the  center  of  the  tuber  a 
mass  of  flaky  starch.  If  the  starch  content  is  too  high, 
the  tubers  will  fall  to  pieces  in  cooking.  The  optimum 
starch  content  is  about  20  per  cent  of  the  peeled  tuber. 

Potatoes  are  of  the  best  quality  when  they  have  ma- 
tured fully  and  have  been  freshly  dug  from  the  soil.  At 
this  time  the  starch  has  been  fully  developed.  Immature 
potatoes  are  usually  high  in  protein,  and  they  frequently 
contain  acids  and  sugars  which  affect  their  flavor.  The 
albuminoids   which   are   frequently   found   in   immature 


264  The  Potato 

tubers  gelatinize  on  cooking  and  make  the  flesh  moist 
and  soggy.  Potatoes  with  a  netted  skin  and  crisp  flesh 
are  most  Hkely  to  be  mealy  when  cooked. 

No  matter  how  carefully  potatoes  are  stored,  there  are 
changes  in  composition  taking  place  all  the  time,  which 
affect  the  quality.  The  tuber,  like  an  apple,  is  a  living 
thing,  and  life  processes  are  going  on  in  it,  though  to  be 
sure  they  are  slow\  As  the  winter  proceeds,  enzymes 
begin  to  work  upon  the  starch  and  sugars  and  to  break 
them  down.  Water  and  carbon  dioxide  are  given  off  as 
a  result.  This  causes  a  loss  of  starch  and  a  shrinkage  of 
the  tuber.  The  sugars  developed  usually  give  the  potato 
a  sweeter  taste  than  is  found  in  the  freshly  dug  tubers. 
Towards  spring  the  potatoes  begin  to  sprout,  and  of 
course  at  this  time  the  chemical  changes  are  rapid.  There 
is  a  rapid  loss  of  mealiness  accompanying  the  sprouting. 

The  method  of  cooking  has  some  effect  upon  quality 
and  food  value,  but  it  is  usually  because  of  a  modification 
of  the  texture  or  the  combination  of  fats  and  other  sub- 
stances with  the  potato  in  the  process  of  cooking.  Boiled 
potatoes  are  most  likely  to  lose  in  food  value  during  cook- 
ing. This  loss  can  be  minimized,  however,  by  cooking 
with  the  skins  on.  Baked  potatoes  lose  very  little,  either 
in  nutrients  or  in  quality,  when  cooked.  They  are 
usually  more  mealy  than  potatoes  which  have  been  boiled 
or  steamed.  ]\Iashed  potatoes  are  usually  seasoned  with 
milk  or  cream  and  butter.  This  makes  them  higher  in  fat 
than  when  they  are  boiled  or  baked.  Potatoes  fried  in 
fat  are  richest  in  food  nutrients.  The  water  is  largely 
extracted  and  much  fat  is  absorbed.  Where  possible,  it 
is  best  to  cook  potatoes  with  their  skins  on.  Experi- 
mental studies  have  shown  that  when  potatoes  are  boiled 
in  the  skins,  practically  no  starch  is  lost  and  only  a 


Uses  of  the  Potato  265 

small  amount  of  the  protein  and  ash  or  mineral  matter. 
Potatoes  which  are  peeled  and  soaked  in  water  before 
cooking  often  lose  as  high  as  7  per  cent  of  their  nutrients. 

USE   FOR  STARCH 

The  principal  article  of  manufacture  from  potatoes  is 
starch.  Until  cornstarch  supplanted  it,  potato  starch 
was  largely  used  in  cooking.  Now  it  is  mainly  employed 
for  making  sizing  for  paper  and  textiles,  and  for  other 
technical  purposes.  Potato  starch  has  also  sometimes 
been  used  as  an  adulterant  of  fine  flours  and  starches. 

The  total  annual  production  of  starch  from  potatoes  in 
the  United  States  is  about  15,500  tons,  of  which  6000 
tons  are  produced  in  the  county  of  Aroostook,  Maine. 
The  soil  of  this  county  is  unusually  well  adapted  to  potato 
growing. 

Unless  the  price  of  marketable  potatoes  is  very  low, 
only  the  small  injured  or  refuse  potatoes  are  sold  to  the 
starch  factory.  Whenever  the  price  of  good  merchant- 
able potatoes  is  above  50  cents  a  barrel,  the  farmers  find 
it  more  profitable  to  sell  directly  to  the  market. 

Process  of  starch  mamifacture 

The  potatoes  which  are  kept  in  a  storehouse  are  carried, 
after  weighing,  to  a  revolving  washer  about  12  feet  long 
and  18  to  24  inches  in  diameter.  They  are  pushed  to 
the  comminutor  through  the  washer  bj^  means  of  a  per- 
forated spiral  or  by  arms  attached  to  a  revolving  axle. 
A  stream  of  water  flowing  in  the  opposite  direction  to 
that  of  the  motion  of  the  potatoes  secures  the  final  w^ash- 
ing  with  clean  water.     By  the  time  the  potatoes  have 


266 


The  Potato 


reached  the  comminiitor  they  are  practically  free  from 
dirt.     A  diagram  of  this  machine  is  shown  in  Fig.  23. 

The  rasping  machine  consists  of  a  cjdinder  about  30 
inches  in  diameter  and  30  inches  long.     It  is  made  of 


Fig.  23.     Machine  for  wasliiug  potatoes. 

wood  and  is  covered  with  pieces  of  sheet  iron  punched 
full  of  holes  about  |  of  an  inch  in  diameter.  These  holes 
have  the  rough  edges  outward.  This  rasping  machine  or 
comminutor  is  shown  in  Fiiis.  24,  25. 


FiQ.  24.     Rasping  cylinder  or  comminutor. 

The  rate  of  revolution  of  the  cylinder  is  about  600  a 
minute.  It  revolves  as  near  a  brace  of  hardwood  as  pos- 
sible, and  the  potato,  being  stopped  from  passing  by  the 
brace,  is  reduced  to  a  fine  pulp  by  the  rapidly  revolving 
drum. 


Uses  of  the  Potato 


267 


From  the  rasper  the  pulp  falls  on  to  a  starch  separator, 
the  bottom  of  which  is  of  fine  wire  gauze  having  30  meshes 
to  the  inch,  the  openings  being  -^  of  an  inch  in  diameter. 
The  separator  is  slightly  inclined,  so  that  the  shaking 


Fig.  25.     Rasping  machine  (cross  section). 

process  gradually  moves  the  pulp  toward  the  lower  end. 
This  separator  is  of  the  same  width  as  the  rasps,  namely, 
about  36  inches,  and  is  about  12  feet  long. 

During  the  progress  of  the  pulp  along  the  separator, 


268 


The  Potato 


jets  of  water  are  thrown  upon  it  from  pipes  arranged 
above.  This  water  detaches  the  starch  granules  from  the 
pulp,  and  the  granules,  being  small,  are  carried  through 
the  meshes  of  the  gauze,  while  the  pulp  is  left  on  the 
screen  and  ejected  finally  at  the  lower  end. 

The  starch  which 

is  carried  through 
by  the  water  falls 
in  large  tanks,  vary- 
ing in  size  from  20 
to  40  feet  in  length 
and  width  and  from 
6  to  8  feet  in  depth. 
The  starch  settles 
to  the  bottom  very 
quickly  and  the  red- 
dish-colored super- 
natant water  can 
be  drawn  off.  In  a 
few  hours  the  starch 
has  all  settled  in  a 
hard,  compact  mass 
at  the  bottom  of 
the  tank.  The  proportion  of  starch  and  water  is  such 
that  4  inches  of  starch  is  overlaid  with  about  6  feet  of 
water. 

The  crude  starch  obtained  in  this  tank  is  then  thrown 
into  another  tank  of  a  similar  size  which  is  fitted  with  a 
revolving  stirrer;  water  is  added  in  large  quantities  at 
the  same  time  and  the  starch  is  beaten  into  a  cream  and 
again  allowed  to  settle.  The  interior  view  of  such  a  tank 
can  be  seen  in  Fig.  26.  This  process  washes  the  starch 
and  removes  the  larger  portion  of  impurities. 


P^iG.  26.     Starch  washer  (interior  view). 


Uses  of  the  Potato  269 

In  the  second  settling  the  pure  starch  is  first  to  go  to 
the  bottom,  and  when  the  water  is  drawn  off  it  is  found  to 
be  covered  with  a  thin  layer  of  starch  mixed  with  various 
forms  of  impurities.  This  layer  is  removed  separately, 
and  the  pure  starch  underneath  is  ready  for  the  drying 
tables. 

The  layer  of  dirty  starch  removed  as  above  indicated 
is  given  a  second  washing  and  if  necessary  a  third,  until 
the  starch  is  thoroughly  cleaned. 

The  most  modern  way  of  drying  is  to  have  the  starch 
stream  out  on  shelves  made  up  of  slats  through  which 
the  dried  starch  can  fall  to  the  shelf  below.  The  drying 
kiln  is  heated  by  steam  pipes  running  along  the  bottom 
underneath  the  shelves.  The  entrance  for  air  is  so 
arranged  that  it  will  come  in  over  the  pipes  and  thus 
become  dried. 

The  starch  is  first  placed  upon  the  upper  floors  on  these 
wooden  slats  which  have  openings  of  about  |  inch.  This 
is  the  coolest  part  of  the  kiln,  so  that  the  starch  wdiich  is 
most  moist  is  subjected  to  the  least  amount  of  heat.  It 
is  not  safe  to  submit  very  wet  starch  to  a  high  tempera- 
ture, for  there  would  be  danger  of  converting  it  into  a 
paste  and  rendering  it  unfit  for  market.  When  the  starch 
is  partially  dried,  it  is  raked  over  the  grated  floor  and  the 
particles  which  are  dry  enough  to  be  easily  detached  fall 
through  and  strike  similar  grates  below.  This  raking 
process  continues  until  the  starch  in  a  fine  powder  form 
reaches  the  lower  fioor  in  a  state  of  dehydration  suitable 
for  barreling.  The  dried  vstarch  is  finally  raked  into  a 
trough  running  alongside  of  the  lower  floor  of  the  kiln, 
and  from  there  it  is  placed  in  the  barrels. 

It  requires  about  12  hours  to  complete  the  drying 
when  the  most  efficient  kilns  are  used,  so  that  the  kilns 


270  The  Potato 

are  oharged  twice  a  day.  The  size  of  the  kilns  is,  of 
course,  proportionate  to  the  capacity  of  the  house.  For 
a  house  using  1200  barrels  of  potatoes  a  day  the  kilns 
are  about  40  feet  long  and  30  feet  wide,  and  the  drying 
shelves  are  about  15  feet  in  height. 

After  the  starch  is  thoroughly  dried,  it  is  placed  in 
heaps  in  order  that  the  moisture  may  be  evenly  dis- 
tributed throughout  the  mass.  It  is  evident  from  the 
method  of  drying  that  some  parts  of  the  starch  come  from 
the  kilns  drier  than  others,  as  this  banking  or  heaping  of 
the  starch  is  very  essential  in  order  to  get  uniformity  of 
moisture.  After  the  mass  of  starch  has  become  uniform 
in  its  content  of  moisture,  it  is  placed  in  barrels  and  is 
then  ready  for  transportation. 


of  potato  starch 

Starch  and  its  by-products  have  many  uses  in  the 
technical  and  industrial  world.  It  possesses  peculiar 
properties  rendering  it  especially  valuable  for  use  in 
print  works.  The  makers  of  prints  are  even  willing  to 
pay  a  considerable  increase  in  price  for  potato  starch 
over  that  which  they  would  have  to  pay  for  starch  from 
Indian  corn. 

In  the  textile  industries,  it  has  come  to  be  used  exten- 
sively and  in  many  ways. 

It  is  used  in  the  manufacture  of  cotton,  woolen,  linen 
and  silk  goods  for  three  distinct  purposes :  as  a  sizing 
for  the  warp  yarn  before  it  is  woven ;  for  finishing  goods 
after  they  have  been  woven ;  in  the  form  of  dextrin  or 
roasted  starch,  as  a  thickener,  or  vehicle  for  applying 
colors  to  the  fabric. 

In  Europe,  especially  in  England,  large  quantities  of 


Uses  of  the  Potato  271 

potato  starch  are  used  for  the  manufacture  of  dextrin  or 
British  gum,  as  it  is  called ;  in  which  form  it  is  used  for 
various  kinds  of  mucilage,  as,  for  instance,  that  applied  to 
postage  and  other  stamps.  The  manufacture  of  dextrin 
of  this  kind  is  an  important  branch  of  the  industries  con- 
nected with  starch. 

The  pomace  or  residue  which  is  left  in  the  manufacture 
of  starch  from  potatoes  has  been  used  to  some  extent  as 
a  food  starch,  and  its  use  as  a  food  will  be  discussed  later 
under  food  for  stock. 


USE   FOR  INDUSTRIAL  ALCOHOL 

Next  to  starch,  industrial  alcohol  is  the  most  important 
product  of  potatoes.  The  potato  is  one  source  of  such 
alcohol,  and  in  Europe,  especially  in  Germany,  is  the  chief 
source.  As  yet  this  sort  of  production  in  connection 
with  potato-growing  has  not  gained  a  foothold  in  the 
United  States.  But  a  brief  survey  of  the  wide  extent  of 
the  practice  in  Germany  may  throw  some  light  upon  its 
possibilities. 

In  Germany,  with  the  extension  of  the  cultivation  of 
the  potato,  which  gives  a  larger  starch  yield  to  the  acre 
than  the  cereals,  the  distillation  of  alcohol  has  become 
largely  an  agricultural  industry.  The  use  in  Germany 
of  potatoes  for  making  alcohol  has  steadily  increased 
from  1,915,800  pounds  in  1855  to  4,706,820,000  pounds 
in  1905.  The  consumption  of  potatoes  has  increased, 
therefore,  nearly  2500-fold  during  50  years.  In  this 
connection  it  must  be  remembered  that  the  starch  con- 
tent of  potatoes  has  also  been  increased.  The  best 
indication  of  the  growth  of  the  potato  alcohol  industry 
is  from  the  output  of  the  finished  product. 


272  The  Potato 

1855 32,757,700  gallons  absolute  alcohol 

1860 42,003,825  gallons  absolute  alcohol 

1865 52,570,825  gallons  absolute  alcohol 

1906  .     exceeded  115,444,445  gallons  absolute  alcohol 

Distillation  is,  therefore,  a  very  important  and  exten- 
sive agricultural  industry  in  Germany.  There  the  potato 
is  the  principal  source  of  alcohol,  and  the  production  of 
spirits  from  other  substances  is  insignificant  in  comparison 
with  that  from  potatoes. 

The  agricultural  significance  of  the  development  of  the 
potato  industry  as  worked  out  in  Germany  is  manifold. 

1 .  All  the  ingredients  taken  from  the  soil  by  the  potato 
are  returned  to  the  soil. 

2.  The  mash,  which  is  the  product  obtained  after  the 
starch  has  been  converted  into  alcohol  and  the  latter  has 
been  removed  by  distillation,  is  a  valuable  feed  for  cattle. 
This  enables  the  farmer  to  maintain  a  large  number  of 
cattle,  and  they  in  turn  provide  the  manure  so  necessary 
for  the  light  soil. 

3.  The  introduction  of  a  cultivated  crop  into  the  rota- 
tion has  been  of  the  greatest  benefit,  because  it  has  made 
possible  larger  yields  of  grain. 

4.  It  has  enabled  the  farmer  to  convert  the  unstable 
crop,  especially  of  those  varieties  of  poor  keeping  quali- 
ties, into  a  stable  product,  alcohol,  which  may  be  held  as 
surplus  stock  for  several  years. 

As  was  shown  above,  potatoes  have  been  used  in  other 
countries  as  a  source  of  cheap  alcohol,  and  the  possibili- 
ties of  its  becoming  a  profitable  enterprise  in  America  are 
very  promising ;  for  conditions  in  this  country  indicate 
that  large  quantities  of  potato  culls  with  the  necessary 
starch  content  are  available  for  this  purpose  at  a  price 


Uses  of  the  Potato  273 

which  would  permit  of  the  profitable  manufacture  of 
alcohol  therefrom.  Experimental  work  at  the  United 
States  distillery  has  shown  that  the  potato  can  be  eco- 
nomically handled  in  manufacturing  alcohol,  and  the 
farmer  can  convert  frosted  or  inferior  grades  of  potatoes 
into  a  source  of  revenue.  It  also  furnishes  in  the  resi- 
due, or  slop,  a  feed  for  stock.  In  recent  years,  many 
persons  have  become  so  much  interested  in  this  industry 
that  it  seems  advisable  to  give  a  somewhat  thorough 
discussion  of  the  methods  of  manufacturing  alcohol  from 
potatoes. 

The  alcohol  from  potatoes  is  a  result  of  the  action  of 
malt  or  acids  on  the  starch,  which  is  turned  into  sugar 
and  then  fermented  to  give  this  final  product.  The  so- 
called  "denatured  alcohol"  is  prepared  by  the  addition 
of  such  ingredients  as  will  make  the  alcohol  unfit  for 
drinking  purposes.  This  alcohol  is  used  extensively  in 
the  manufacture  of  varnish,  explosives,  chemicals  and 
many  other  commercial  substances.  It  may  also  be  used 
in  various  household  appliances,  both  for  lighting  and 
heating  purposes,  and  with  much  more  safety  than  either 
kerosene  or  gasoline. 

This  discussion  is  limited  to  the  methods  which  can  be 
used  upon  a  farm,  or  by  a  farm  community,  in  a  small 
distillery  handled  by  the  farmer  himself.  The  potatoes 
should  of  course  have  enough  starch  to  be  worth  using 
for  this  purpose.  From  experiments  it  has  been  deter- 
mined that  there  should  not  be  less  than  6  per  cent  of 
sugar  or  starch  before  the  materials  can  be  considered 
suitable  for  the  profitable  manufacture  of  alcohol. 


274  The  Potato 

The  manufacture  of  alcohol  from  potatoes 

The  first  essential  in  manufacturing  alcohol  from  potatoes  is  that 
the  distillery  should  be  centrally  located  in  a  potato-raising  country ; 
and  seconflly,  the  railroad  facilities  should  be  such  tliat  delivery  of  raw 
materials  and  feed,  and  the  marketing  of  the  finished  product,  can 
be  done  at  a  minimum  expense.  An  abundant  supply  of  cold  soft 
water  is  of  almost  equal  importance.  It  is  desirable  that  the  plant 
be  near  a  creek  or  stream  from  wliich  water  may  be  obtained  and  into 
which  it  may  be  drained  after  serving  its  purpose  in  the  distillery. 

As  the  distillery  cannot  be  run  tliroughout  the  entire  year,  the 
machinery  should  be  simple,  practical  and  economical.  Advantage 
should  be  taken  of  the  laws  of  gravity  to  save  pumping  whenever 
possible.  This  can  be  done  by  arranging  the  apparatus  so  that  each 
operation  will  be  on  a  lower  level  than  the  preceding  one;  thus 
by  elevating  the  raw  material  to  a  height  suitable  for  the  first  opera- 
tion, it  will  flow  from  one  apparatus  to  another  by  its  own  weight. 
All  machinery  requiring  steam  should  be  placed  close  to  the  boiler 
so  as  to  avoid  condensation  caused  by  long  pipe  connections.  Ex- 
haust steam  from  the  engines  and  pimips  should  be  used  in  the  dis- 
tillery apparatus  and  the  hot  water  from  the  condenser  should  be 
utilized  as  feed  water  for  the  boiler.  Each  piece  of  apparatus  should 
have  a  capacity  equal  to  the  exact  amount  of  work  it  is  expected  to 
do,  the  only  exception  to  this  being  the  boiler,  upon  the  efficiency  of 
which  depends  the  proper  working  of  each  piece  of  apparatus.  The 
boiler  should  be  of  a  slightly  larger  capacity  than  is  actually  required. 

This  following  data  on  the  cost  of  a  distillery  are  of  a  supposed 
plant  which  has  a  capacity  for  handling  8000  poimds  of  potatoes 
in  one  working  day  of  10  hours.  The  building  is  one  story  high, 
with  a  ground  space  of  1000  square  feet.  The  walls  are  constructed 
of  any  available  material.  In  many  cases  farm  buildings,  such  as 
barns  and  the  like,  could  be  used.  Such  a  building  will  not  cost 
more  than  $1500.  Total  cost  of  machinery  and  equipment  not 
inclusive  of  motor  power  is  about  $9000.  One  75-horsepower 
boiler  and  a  25-horsepower  engine  will  be  required  and  will  cost  about 
S1500.     This  would  make  a  total  investment  of  about  $12,000. 

A  day's  expenses  will  include  the  cost  of  potatoes,  barley,  fuel 
and  labor.  Cull  potatoes  can  be  delivered  at  a  distillery  in  some 
potato-growing  districts  at  2.5  cents  for  100  pounds.  At  this  rate 
the  raw  material  for  a  day's  run  of  8000  pounds  will  cost  $20.     To 


Uses  of  the  Potato  275 

convert  the  starch  of  the  potatoes  into  sugar,  there  will  be  needed 
the  green  malt  yielded  by  120  pounds  of  barley,  which  at  70  cents  a 
bushel  will  cost  $1.75. 

The  cost  of  fuel  varies  with  the  fireman,  but  with  proper  care  and 
efficient  use  one  ton  at  $4  should  be  enough  for  a  day's  operation. 
Three  men  will  be  required,  consisting  of  a  fireman  and  two  laboi'ers. 
This  will  total  up  to  about  $33  for  daily  operating  expenses. 

Operating  a  distillery.  —  The  first  process  is  to  wash  and  then 
cool  the  potatoes  so  that  the  starch  present  can  be  thoroughly 
converted  into  sugar  by  the  action  of  the  malt.  The  potatoes  are 
placed  in  a  vacuum  cooker  and  steamed  until  they  are  thoroughly 
cooked.  The  steam  pressiu-e  in  the  cooker  is  allowed  to  rise  to  50  or 
60  pounds.  The  entire  time  required  for  warming  the  potatoes  and 
reaching  the  maximum  pressure  should  be  about  one  hour.  The 
potatoes  are  stirred  and  the  pressure  held  for  about  ten  more  minutes 
to  insure  a  good  cooking  of  the  starch.  Then  the  temperature  of 
the  cooked  potatoes  is  allowed  to  fall  to  212°  F.  The  temperature 
of  the  cooked  potatoes  is  further  reduced  by  means  of  the  vacuimi 
pump  to  140-145  F.°  at  which  point  the  malt  necessary  to  change 
the  starch  to  sugar  is  added.  About  2  pounds  of  malt  is  added  for 
each  100  jwunds  of  potatoes  mashed.  The  green  malt  is  crushed 
between  rolls,  while  dried  malt  is  ground  in  a  mill  before  using. 
About  fifteen  minutes  before  the  mash  in  the  cooker  is  ready  for 
malting,  the  malt  already  ground  is  mixed  with  water  at  the  rate  of 
1  gallon  of  water  to  2.5  pounds  of  dried  malt,  or  f  gallon  of  water  to 
same  amount  of  green  malt.  This  is  prepared  in  a  tub  above  the  cooker 
and  is  dropped  into  the  cooker  when  the  temperature  is  down  to  140° 
to  145°  F.  The  diastase  in  the  malt  will  dissolve  the  cooked  starch 
and  convert  it  into  a  fermentable  sugar  in  about  fifteen  or  twenty 
minutes,  during  which  time  the  mash  should  be  constantly  stirred. 
This  is  kept  up  until  the  test  for  complete  conversion  shows  no  starch. 
This  test  consists  in  filtering  a  little  of  the  mash  into  a  white  porce- 
lain dish  and  adding  a  few  drops  of  iodine  solution  (2.5  drams  potas- 
sium iodide  and  75  grains  iodine  to  1  quart  water  and  shake).  If 
the  mixture  is  blue,  it  shows  the  presence  of  starch,  and  it  is  then 
necessary  to  add  more  malt,  or  allow  more  time  for  conversion.  The 
cleaned  mash  is  pumped  tlirough  the  mash  cooler,  where  it  is  re- 
duced to  the  "pitching"  (this  means  temperature  in  which  yeast 
can  ferment)  temperature,  by  circulating  a  constant  stream  of  cold 
water  aroimd  the  pipes  through  which  the  mash  goes.     Tliis  tempera- 


276  The  Potato 

turemost  favorable  to  fermentation  is  between  60°  and  70°  F.,  depend- 
ing on  the  weather  conditions  and  vohime  of  the  mash.  At  the  same 
time  the  mash  is  run  through  the  fermenter  the  yeast  mash  (about 
3  per  cent  by  volume  of  the  main  mash)  is  also  added.  It  is  prepared 
in  a  tube  above  the  fermenter  and  can  be  dropped  into  it. 

Fermenting  the  mash.  —  After  the  yeast  and  mash  are  in  the  fer- 
menter, the  process  of  fermentation  will  begin  and  the  sugar  in  solu- 
tion will  be  broken  down  into  alcohol  and  carbon  dioxide  gas.  The 
gas  goes  out  into  the  air,  and  the  alcohol  remains.  At  this  point, 
it  is  important  to  know  the  gravity  and  acidity  of  the  "set  mash"  — 
as  it  is  now  called.  The  specific  gravity  indicates  the  amoimt  of 
sugar  and  is  ascertained  as  follows :  Stir  mash  and  filter  small  por- 
tion through  cheesecloth  into  a  cylinder.  A  Balling  saccharimeter  is 
placed  in  the  filtered  liquid.  The  reading  at  the  level  of  the  liquid 
should  be  16°  to  18°,  showing  that  the  mash  contains  16  to  18  per 
cent  of  solids,  most  of  which  is  sugar.  The  acidity  of  the  set  mash  is 
determined  by  neutralizing  a  small  portion  of  the  mash  in  a  normal 
solution  of  sodium  hydroxide,  and  the  amount  of  the  latter  required 
will  represent  the  acidity  of  the  mash.  It  is  done  in  the  following 
way :  20  cubic  centimeters  of  the  filtered  Hquid  is  placed  in  a  beaker 
and  the  sodium  hydroxide  is  blowly  dropped  in  from  a  burette  until 
the  filtered  liquid  has  been  neutralized  and  will  not  turn  blue  litmus 
red  or  red  litmus  blue.  The  number  of  cubic  centimeters  of  sodium 
hydroxide  used  will  represent  the  acidity  of  the  mash.  After  the  mash 
has  been  set  for  ten  or  twelve  horn's,  the  fermentation  will  become 
vigorous  and  the  temperature  will  rise.  It  should  not  be  allowed 
to  go  above  80°  F.  or  much  of  the  alcohol  will  evaporate.  To  keep 
the  mash  cool,  a  coil  with  cold  water  passing  tlirough  it  is  slowly 
raised  and  lowered  through  the  mash.  The  fermentation  is  allowed 
to  continue  at  a  temperature  of  60°  to  80°  F.  for  72  hours.  The 
gravity  should  fall  and  the  acidity  remain  about  the  same  diu"ing  the 
process.  The  tests  should  be  made  every  24  hours.  If  the  acidity 
rises  too  much,  the  fermenters  are  scrubbed  clean  with  a  5  per  cent 
solution  of  formalin  or  other  disinfectant.  This  will  clean  out  the 
butyric  acid  which  often  is  the  cause  for  raised  acidity. 

Distilling  the  alcohol.  —  In  Fig.  27  is  shown  a  distilling  apparatus 
adapted  for  the  economic  separation  of  alcohol  from  the  mash.  It 
is  not  complicated,  as  one  would  think  at  a  first  glance,  but  is  very 
simple.  The  fermented  mash  is  slowly  pumped  into  a  distilling  ap- 
paratus, where  it  is  brought  into  contact  with  live  steam,  which  boils 


Uses  of  the  Potato 


277 


Fig.  27.  —  Distilling  apparatus  for  making  alcohol  from  potatoes. 


278  The  Potato 

it  and  carries  away  the  alcohol  in  vapor  form,  which  in  turn  is  passed 
through  a  condenser,  where  it  is  reduced  to  a  liquid.  The  distilling 
apparatus  consists  of  two  copper  columns,  A  and  B,  A  being  to  dis- 
til the  alcohol  from  the  mash  and  B  where  it  is  redistilled  and  raised 
to  desired  strength.  The  fermented  mash  is  continually  discharged 
from  pump  1  and  pipe  2  into  mash  heater  3.  This  heater  is  made 
up  of  a  series  of  tubes  through  which  the  mash  gas  goes  and  around 
which  the  vapors  from  the  boiling  mash  are  passed  when  going  from 
A  to  B.  The  heated  mash  leaves  3  through  pipe  4  and  comes  in  con- 
tact with  steam.  The  mash  goes  tlirough  a  series  of  chambers,  where 
it  is  boiled  and  the  alcohol  relieved  from  it.  This  mash  takes  a  down- 
ward course  from  one  chamber  to  another,  and  its  course  may  be 
followed  by  the  shaded  portions  in  A .  By  the  time  it  reaches  the  bot- 
tom, the  mash  will  lose  all  its  alcohol,  and  this  mash  will  be  automati- 
cally discharged  through  5.  A  small  portion  of  the  vapors  will  be 
sent  through  pipe  6  to  the  condenser  7,  and  be  tested  to  see  whether 
any  alcohol  is  being  lost  in  the  "slop,"  as  the  discharged  mash  is 
called.  The  steam  necessary  to  boil  the  mash  comes  into  the 
bottom  chamber  tlirough  8,  and  it  boils  the  mash  in  this  chamber  and 
passes  upward,  boiling  the  descending  mash  in  the  various  chambers 
and  carrying  with  it  the  vapors.  The  plates  within  column  A  are 
so  perforated  as  to  allow  the  ascent  of  the  vapors  through  it,  but 
do  not  allow  the  mash  to  fall  through  it,  because  of  the  steam  pres- 
sure. The  vapors  rise  up  through  A  and  go  through  pipe  9  to  the 
heater  3,  where  they  are  circulated  around  the  tubes  and  then  carried 
through  pipe  10  over  to  B.  The  vapors  coming  from  A  contain  a 
considerable  amount  of  moisture  and  other  impurities  which  are 
freed  in  B,  which  contains  a  series  of  chambers  upon  each  of  which  is 
carried  about  3  inches  of  liquid.  The  plates  are  not  perforated  in  this 
column,  but  the  vapors  ascend  tlirough  a  central  pipe  and  are  de- 
flected downward  by  a  hood  over  the  pipe  in  each  chamber  and  are 
forced  to  boil  their  way  through  the  liquid  in  each  plate.  The 
arrows  show  their  courses.  These  vapors  become  piu-er  as  they 
ascend  until  they  reach  the  top  chamber,  from  which  they  are  de- 
livered to  pipe  11  and  thus  into  a  cooler  12,  where  they  are  partially 
cooled.  From  the  cooler  they  pass  into  pipe  13  and  through  it  to 
the  condenser  14,  where  they  are  reduced  to  a  liquid.  This  cooling 
and  reducing  is  done  by  circulating  cold  water  around  the  tubes  con- 
taining the  vapors.  The  condensed  vapor  or  alcohol  is  drawn  off  at 
the  bottom  of  the  condenser  and  allowed  to  flow  tlirough  the  test  box 


Uses  of  the  Potato  279 

15,  where  it  can  be  examined   for  its  purity  and  strength.     The 
steam  pressure  in  the  apparatus  is  registered  by  the  pressure  gauge 

16.  The  alcohol  afterwards  passes  tlirough  the  test  box  into  the 
storage  tank  17  to  be  denatured. 

Wood  alcohol  and  benzin  are  generally  used  as  denaturing  agents, 
though  other  ingredients  may  be  used.  The  ingredients  used  must 
be  authorized  by  the  Bureau  of  Internal  Revenue. 

Preparation  of  green  barley  malt.  —  There  are  two  operations  — 
the  first  being  to  steep  or  soak  the  grain,  and  the  second,  sprouting 
or  growing  it.  The  steeping  consists  of  soaking  the  grain  in  water 
until  it  has  absorbed  sufficient  moisture  to  enable  it  to  sprout  when 
spread  upon  the  malting  floor.  Good  barley  malt  can  be  obtained 
from  a  good  grade  of  barley  properly  steeped  (for  two  or  tliree  days) 
and  grown  for  a  long  interval  of  time  (12  to  20  days)  with  a  fair 
amount  of  moisture  at  a  temperature  not  to  exceed  60°-63°  F.  The 
malt  should  be  thoroughly  crushed  before  using. 

Control  of  operation.  —  It  is  advisable  to  operate  a  distillery  only 
during  the  colder  months,  for  instance  from  early  autumn  until  late 
spring.  During  this  time  the  temperature  of  the  cooling  water  will 
be  considerably  lower,  and  the  amount  of  water  required  correspond- 
ingly less,  and  the  time  required  for  cooling  decidedly  shortened. 
This  means  a  shorter  working  day  and  consequently  less  Avear  on  the 
machinery  and  a  considerable  saving  of  fuel.  It  is  essential  that  a 
distillery  be  oj^erated  daily  and  not  intermittently,  as  each  day's  work 
depends  in  a  greater  or  less  degree  both  upon  that  of  the  preceding 
and  the  following  day.  Another  very  important  point  is  cleanliness, 
and  upon  this  depends  the  final  yield  of  alcohol  in  a  great  measure. 
Many  injurious  organisms  will  breed  and  work  into  the  mash  and 
hinder  the  process  of  fermentation.  This  may  be  remedied  by  run- 
ning water  through  the  apparatus  at  the  end  of  the  day's  work,  and  the 
walls  of  the  building  should  be  kept  from  mold  by  whitewashing. 

Preparation  of  a  potato-yeast  mash.  —  The  yeast  mash  is  prepared 
in  a  wooden  tub  equipped  with  a  rake  for  stirring  and  with  proper 
piping  for  heating  and  cooling.  The  volume  of  the  yeast  should  be 
from  2  to  3  per  cent  of  the  main  mash  to  be  fermented  and  increased  to 
ten  times  that  of  the  yeast  mash  used  to  start  it.  Rye  is  best  used 
to  start  with,  and  later  the  potatoes  may  be  substituted.  The  rye 
and  malt  are  mashed  together.  The  malt  should  be  left  to  work  for 
about  three  hours,  by  which  time  the  formation  of  the  sugar  will  be 
complete.     The  gravity  should  be  20°-24°  Balling.     Then  the  mash 


280 


The  Potato 


is  soured  by  the  addition  of  some  acids  (lactic  acid  is  best)  which  will 
suppress  organisms  which  infect  starchy  materials.  It  will  take  be- 
tween 24  and  48  hours  to  reacli  the  right  acidity,  which  is  2.5  or  3  cubic 
centimeters.  Then  heat  and  then  cool.  When  temperature  is  about 
90°  F.,  add  the  yeast  (about  10  per  cent  of  volume  of  mash).  Then 
reduce  the  temperature  to  60°-70°  F.  Allow  to  ferment  for  24  hours, 
diu"ing  which  time  the  temperature  will  rise,  but  never  allow  it  to  get 
above  90°  F.  Then  this  can  be  used  in  needed  quantities  to  be  added 
to  the  main  mash. 

USE   AS   STOCK   FOOD 

The  value  of  the  potato  as  a  food  is  great,  for  it  is  a 
very  concentrated  starchy  food.  When  fed  alone,  it  is  in- 
capable of  supplying  all  of  the  wants  of  the  body.  Ex- 
periments by  Girarde  showed  that  the  feeding  of  too 
many  potatoes  to  stock  would  decrease  the  digestibility 
of  the  protein,  the  fat  and  the  crude  fiber : 


Table 

XXII 

1 

s 
S 

1 

i 

5§ 

g 

a 

W 

o 

1 

Q 

^ 

(X, 

6 

Per 
Cent 

Per 

Cent 

Per 

Cent 

Per 

Cent 

Per 

Cent 

Per 

Cent 

Per 

Cent 

Potatoes      .     .     . 

Pigs 

97.0 

84.5 

82 

91.8 

44.6 

Potatoes  cooked  . 

Pigs 

95.0 

82.0 

80 

97.6 

40.0 

Potatoes  dried  and 

ground     .     .     . 

Sheep 

80.1 

81.5 

19.5 

42.0 

(From  S.  Fraser.     "The  Potato.") 

It  was  also  found  to  have  increased  the  time  of  churn- 
ing butter  from  36  to  86  minutes.  There  was  no  effect 
on  the  milk  composition,  but  it  did  affect  its  behavior 
towards  rennet,  injuring  the  milk  for  cheese-making. 

Potatoes  when  fed  to  pigs  have  been  shown  to  be  al- 
most entirely  digestible. 


Uses  of  the  Potato  281 

Snyder  found  that  potatoes,  when  fed  with  grains  or 
some  milled  products  hke  oil  meal,  beans  or  good  wheat 
screenings,  were  very  suitable  for  fattening  purposes. 
In  experiments  with  sheep  and  cattle  a  ration  composed 
chiefly  of  potatoes  afforded  rapid  gains  in  live  weight,  a 
large  percentage  in  dressed  weight  of  the  slaughtered 
animals  and  flesh  of  excellent  quality. 

Experiments  in  Minnesota  have  shown  that  potatoes 
are  very  digestible ;  when  100  pounds  are  fed  to  pigs, 
23.8  pounds  dry  matter  are  digested,  while  only  75  pounds 
are  indigestible.  At  the  Hohenheim  and  Proskern  sta- 
tions, the  results  on  this  question  showed  that  they  may, 
for  practical  purposes,  be  assumed  to  be  completely  diges- 
tible. Snyder,  at  the  Minnesota  Station,  found  that 
though  cooked  potatoes  were  eaten  in  greater  quantities, 
the  digestibility  was  not  increased. 

Thus,  it  can  easily  be  seen  that  potatoes,  especially 
when  abundant  and  low  in  price,  may  be  fed  to  all  kinds 
of  stock.  In  France,  Girarde  fed  55  to  66  pounds  of 
cooked  potatoes  a  day  to  fattening  steers  and  4^  to  6^ 
pounds  to  sheep.  Von  Fanche  found  uncooked  potatoes 
good  for  all  stock  except  pigs.  He  fed  60  pounds  raw 
potatoes,  6  pounds  oil  meal  and  9  pounds  clover  hay  with 
salt  to  a  1000-pounds  live  weight  a  day  to  fattening  steers. 
For  milch  cows,  25  pounds  daily  to  a  1000-pounds  live 
weight  is  the  limit.  For  yearling  ewes  and  wether  sheep 
25  pounds  to  a  1000-pounds  live  weight  a  day  is  advised, 
and  for  fattening  sheep  40  pounds.  For  horses  about 
12  pounds  to  a  1000-pounds  live  weight  may  be  given 
with  other  food. 

Stock  should  not  be  watered  soon  after  feeding  potatoes, 
but  preferably  about  i  hour  before  feeding.  Potatoes 
are  not  valuable  as  a  food  for  young  animals  as  they  are 


282 


The  Potato 


deficient  in  protein  and  ash,  hence  should  not  be  fed  to 
growing  cattle  under  two  years  old,  lambs  and  young 
pigs,  unless  in  small  amounts. 


Alcohol  slops  or  residue 

The  residue  remaining  from  the  production  of  alcohol 
contains  all  the  constituents  of  the  materials  employed, 
except  that  portion  of  the  sugars  and  starch  which  was 
converted  into  alcohol  during  the  fermenting  period. 
This  "slop"  has  been  found,  both  in  this  country  and 
abroad,  to  be  a  feeding  stuff  of  high  value,  and  should  be 
fed  to  the  stock  which  furnishes  the  fertilizer  for  the 
potatoes  to  be  used  in  the  distillery. 


Table  XXIII 
Composition  of  the  Slop 

Ash 

Protein 
N.X6.25 

Fat 

SUQAB 

Stakch 

Crude 
Fiber 

N.  F.  E. 

Potato.     .     . 
Potato  skins  . 
Slops     .     .     . 

Per  Cent 

4.39 

6.51 

11.26 

Per  Cent 

10.06 
21.87 
30.00 

Per  Cent 
0.29 

2.55 
0.69 

Per  Cent 

1.59 
1.44 
2.29 

Per  Cent 

70.35 
8.65 
2.98 

Per  Cent 
2.26 

20.69 
6.54 

Per  Cent 

10.55 
28.40 
46.24 

(From  the  U.  S.  D.  A.,  Farmers'  Bui.  410.) 


This  table  shows  that  the  dry  substance  of  the  slops  is 
a  higher  nitrogenous  food  than  the  potato.  It  is  due  to 
the  fermentation  of  the  starch  and  sugar  resulting  in  a 
concentration  of  the  nitrogenous  material. 


Uses  of  the  Potato  283 

Potato  pomace 

Potato  pomace  is  the  residue  which  is  left  in  the  manu- 
facture of  starch  from  potatoes.  It  contains  nearly  all 
of  the  fiber,  protein,  fat  and  a  large  part  of  the  starch 
found  in  the  fresh  potato.  As  it  comes  from  the  factory 
it  has  incorporated  in  it  a  large  amount  of  water. 

In  this  country  this  pulp  mass  goes  to  waste,  but  in 
Europe  the  potato  and  beet  residue  are  rather  extensively 
used  as  feeds  in  the  wet  condition,  80  pounds  to  125 
pounds  being  fed  to  cattle  daily  a  head.  There,  however, 
the  factories  are  running  throughout  the  year,  and  the 
residue  can  be  fed  in  the  wet  state.  But  here  this  is  not 
possible,  and  as  the  wet  residue  cannot  keep,  some  method 
must  be  devised  to  dry  it  out,  for  in  the  dry  state  it  will 
keep  well. 

Poultry  food 

T.  W.  Saunders,  in  his  book  on  the  potato,  very  highly 
recommends  the  use  of  potatoes  as  a  poultry  food.  When 
given  in  correct  proportion,  it  will  do  good  in  a  food.  The 
starchy  part  of  the  potato  is  mainly  used  in  maintaining 
the  heat  of  the  body.  It  is  cheap  and  easy  to  prepare 
and  generally  liked  by  all  classes  of  poultry.  To  get  the 
right  proportions,  of  course,  one  must  take  into  considera- 
tion the  condition  of  the  birds,  weather,  temperature, 
method  of  housing,  extent  of  liberty  allowed  and  whether 
the  birds  are  expected  to  produce  eggs  or  to  lay  on  fat 
and  flesh. 

A  cheap  good  diet  used  for  layers  that  are  at  liberty  is 
equal  parts  by  weight  of  potato  and  bran.  The  potato 
should  be  boiled,  and  the  latter  mashed  into  the  potato 
while  hot  and  the  mixture  given  warm.     If  the  weather 


284.  The  Potato 

is  cold,  add  some  linseed  oil  or  fat.  For  confined  layers, 
the  proportion  of  potato  should  be  reduced.  Malt  culms 
or  sprouts  are  very  good  in  combination  with  potatoes. 

Indian  meal,  barley  meal  and  rice  meal  should  not  be 
fed  in  combination  with  potatoes,  for  they  lack  nitrogen 
matter. 

For  fattening  poultry,  large  amounts  of  potato  can  be 
used.  Ducks,  geese  and  turkeys  fatten  well  on  a  mixture 
of  potato  and  midds. 

Dried  dessicated  potatoes 

In  Germany  the  manufacture  of  potato  cakes  is  estab- 
lished, and  these  can  be  used  as  a  food.  The  cakes,  of 
course,  are  much  smaller  in  bulk  than  the  fresh  potatoes, 
but  after  the  soaking  in  water  before  using,  their  original 
character  is  regained.  While  the  flavor  and  appearance 
cannot  equal  those  of  good  fresh  potatoes,  they  are  con- 
sidered appetizing  and  acceptable  where  fresh  ones  are 
unobtainable.  In  this  form  they  can  be  easily  preserved 
in  the  tropics  and  in  the  arctic  region  and  thus  furnish 
an  excellent  article  of  diet  in  a  convenient  form  for  trans- 
portation. 

Potato  flour 

In  Germany  the  manufacture  of  potato  flour  is  very 
much  advanced.  Rye  flour  is  improved  for  baking  by 
its  addition.  During  the  winter  of  1914-1915,  when 
there  was  a  shortage  of  flour,  owing  to  the  European 
war,  potato  flour  was  used  to  make  cakes  and  bread. 
Cakemakers  and  confectioners  used  it  mixed  with  wheat 
flour. 


Uses  of  the  Potato  285 


REFERENCES 

Canon,  Helen. 

1915.     Potatoes  in  the  Dietary.     Cornell  Reading  Course  Bui., 
Food  Series  No.  15. 
Oilman,  J.  W. 

1905.     Quality  in  Potatoes.     Cornell  Bui.  230,  pp.  503-525. 

GiRARDE,   A. 

Potatoes  as  a  Food  for  Cattle  and  Sheep.     Journ.  Agr. 
Proc.  59  (1895),  No.  20,  pp.  709-712. 
Grubb,  E.  H. 

1912.     The  Potato.     N.  Y.  (Doubleday),  p.  545. 
Henslow,  G. 

1910.  Origin  and  Best  of  Our  Garden  Vegetables   and  Their 

1911.  Dietetic  Values.     Roy.  Hort.  Soc.  Journ.,  36,  pp.  345- 
346. 

Lang  WORTHY,  C.  F. 

Potato  as  a  Food.     U.  S.  D.  A.,  Farmers'  Bui.  295. 
NiviERE  and  Humbert. 

1895.  Manufacture  of  Potato  Cake.     Abs.  in  Joiu-n.  Bd.  Agr.,  2 

(1895),  No.  2,  pp.  190. 
Parow,  E.     Potato    Drying   in    (Germany.     Mitt.   Deut.    Landw. 

Gesell.,  21  (1906),  No.  25,  pp.  264-266. 
Searl,  O.,  Springer,  J.,  and  Kjus,  M.  J.     Manufactiue  of  Potato 

Starch.     Tidsske-Norske  Taudbr.,  4  (1897),  No.  5,  pp. 

203-208. 
Skinner,  A.  P. 

1910.     Manufacture    of    Potato    Spirit     in     Germany.      Daily 

Cons,  and  Trade  Repts.    (U.  S.)   13,  No.   148,   1167- 

1169. 
Smith,  C.  D. 

1896.  Feeding  Value  of  Potatoes.     Mich.  Sta.  Rpt.  107. 
Snyder,  H.     The  Composition  and  Digestibility  and   Food  Value 

of  Potatoes.     Minn.  Sta.  Rpt.  8  (1895),  83-96. 
Wente,  a.  O.     Potato  Culls  as  a  Source  of  Industrial  Alcohol. 

U.  S.  D.  A.,  Farmers'  Bui. 
Wiley,  H.  W.    The  Manufacture  of  Starch  from  Potatoes   and 

Cassard.     U.  S.  D.  A.,  Div.  of  Chem.,  Bui.  58,  pp. 


286  The  Potato 

Wiley,  H.  W.     Potato  as  a  Food.     Compt.  Rend.  Acad.  Sci.,  Paris 

(1897),  No.  1,  pp.  43,  4G. 
Wiley,  H.  W.     Potato  as  a  Food  for  Milch  Cows.     Journ.  Agr. 

Pract.,  58  (1894),  No.  28,  pp.  46-17. 
Wiley,  H.  W.     Potatoes  as  a  Food  for  Beef  Cattle  and  Sheep. 

Journ.  Agr.  Pract.,  58  (1894),  No.  28,  pp.  43,  46. 


CHAPTER  XV 
COST  OF  GROWING  POTATOES 

The  cost  of  growing  potatoes  is  very  variable,  depend- 
ing upon  many  factors.  The  cost  not  only  varies  among 
different  sections  of  the  country,  but  among  farmers  in 
the  same  section.  The  price  of  land,  use  of  machinery, 
amount  of  spraying  and  extensiveness  of  operations  are 
only  a  few  of  the  factors  which  determine  the  cost.  When 
figures  are  compared  from  many  areas,  however,  a  con- 
siderable uniformity  is  found  to  exist. 

Costs  are  given  in  the  following  pages  from  widely 
separated  areas.  They  will  give  the  reader  a  fairly 
accurate  idea  of  the  average  expense  involved  in  growing 
an  acre  of  potatoes  in  different  regions. 

Place  —  Twin  Falls  County,  Idaho. 

Authority  —  Grubb  and  Guilford,  "The  Potato." 

Detailed  cost  of  producing  a  150-bushel  crop  as  fol- 
lows :  — 

Plowing $3.00 

Harrowing .75 

Floating 1.00 

Seed,  average  planting  700  pounds  at  2  cents  14.00 

Planting 2.50 

Irrigating  first  year 5.00 

Cultivating  three  times  at  50  cents   ....  1.50 

Digging 1.50 

Picking  —  150  bushels  at  4  cents       ....  6.00 

Sacks  —  75  at  7  cents 5.25 

Hauling  to  pit 2.00 

Total .S44.00 

287 


288  The  Potato 

"If  potatoes  are  worth  50  cents  a  bushel,  this  crop 
would  sell  for  $75,  leaving  a  profit  of  $30.50  per  acre, 
not  deducting  rent  or  interest  or  taxes. 

"If,  however,  the  grower  produces  a  600-bushel  crop, 
the  cost  of  producing  (figuring  twice  as  much  seed  and 
increased  cost  of  the  operations)  would  be  about  $95.75. 
The  crop  would  sell  (at  50  cents  a  bushel)  for  $300,  leav- 
ing a  profit  of  $204.25." 

Place  —  Colorado. 

Authority  —  Greeley  Commercial  Club. 

Plowing $2.50 

Leveling  and  harrowing 1.00 

Seed 5.00 

Planting 1.50 

Cultivating 2.50 

Irrigating       1.50 

Digging 7.50 

Sacks 7.50 

Marketing 6.00 

Total $35.00 

"This  estimate  is  based  on  what  is  considered  a  good 
yield  of  from  200  to  300  bushels  per  acre.  The  first  six 
items  are  practically  uniform  whatever  the  yield  may  be, 
while  the  last  three  depend  upon  the  yield  per  acre,  so 
that  a  poor  yield  or  a  failure  reduces  the  cost  per  acre 
by  about  one-half  and  an  extremely  large  yield  increases 
it  accordingly. 

"  The  price  of  Colorado  potatoes  has  a  wide  range  from 
year  to  year,  but  the  average  price  for  the  past  ten  years 
has  been  65  cents  per  hundred  pounds." 

Place  —  Kansas.  Forty  representative  growers  from 
thirty-two  different  counties. 

Authority  —  Report  of  Kansas  State  Board  of  Agri- 
culture, 1904. 


Cost  of  Growing  Potatoes  289 

Average  cost  of  plowing $1.20 

Harrowing 54 

Seed 7.25 

Planting 1.35 

Cultivating 1.66 

Digging  and  marketing 8.85 

Wear  and  tear  of  tools  and  rental  of  land  or 

interest  on  its  value 4.42 

Total  cost  per  acre,  or  122  bushels       .  5»25.27 

Averages  of  other  items,  gathered  from  those  furnish- 
ing the  forty  foregoing  reports,  are  as  follows : 

Average  number  of  years  each  of  the  forty  reporters  has 

raised  potatoes  in  Kansas 18 

Average  number  of  acres  raised  by  each  annually      ...  26 

Average  quantity  of  seed  planted  per  acre  (bushels)       .     .  9 

Average  yield  per  acre  (bushels) 122 

Average  value  of  potato  land  per  acre $60 

Statements  of  ten  of  the  growers  reporting  who  are 
most  extensively  producing  potatoes  for  commercial 
purposes,  in  the-Kaw  Valley,  average  as  here  shown  : 

Average  cost  of  plowing $1.45 

Harrowing .51 

Seed 8.05 

Planting .65 

Cultivating 1.46 

Digging  and  marketing 11.00 

Wear  and  tear  of  tools  and  rental  of  land  or 

interest  on  its  value 6.85 

Total  cost  per  acre,  or  154  bushels       .  $29.97 

Average  number  of  years  each  of  these  ten  reporters  has 

raised  potatoes  in  Kansas 18.0 

Average  number  of  acres  raised  by  each  annually     .     .  80.0 

Average  quantity  of  seed  planted  per  acre  (bushels)     .  10.4 

Average  yield  per  acre  (bushels) 153.7 

Average  value  of  potato  land  per  acre $105.00 

u 


290  The  Potato 

Place  —  Ohio. 

Authority  —  Terry,  T.  B.,  and  Root,  A.  I.,  "Potato 
Culture." 

Yield  per  acre  —  250  bushels. 
Average  price  —  40  cents. 
Profit  per  acre  —  $61.06. 
Detailed  cost  as  below  :  — 

Plowing $2.00 

Harrowing  with  Thomas  and  three  horses         .33 

RoUing 25 

Eight  bushels  seed  at  50  cents,  average       .       4.00 

Cutting  to  one  eye 1.50 

Planting  with  planter 1.00 

Harrowing  three  times 45 

Harro^ving  four  times  with  weeder     ...         .80 
Cultivating  eight  times,  once  in  a  row    .     .       3.36 

Bugs 2.00 

Hand  pulling  or  cutting  weeds 75 

Digging  with  four  horses 2.50 

Picking  up  and  storing 3.00 

Marketing,  three-mile  haul 6.00 

Manure 5.00 

Interest  on  value  of  land  $100,  at  6  per  cent       6.00 

$38.94 

Dodge  says:  "The  more  expensive  method  of  growing 
potatoes  usually  gives  a  yield  of  275  bushels  or  more  to 
the  acre.  Unless  an  application  of  barnyard  manure  is 
made  in  addition  to  the  expense  estimated  at  an  added 
cost  of  from  $5  to  $10  per  acre,  the  less  expensive  method 
rarely  produces  more  than  125  bushels  per  acre  and  in  a 
great  many  instances  decidedly  less  than  100  bushels  per 
acre.  The  increase  in  yield  as  a  result  of  the  more  costly 
method  is  sufficient  to  more  than  pay  the  difference  in 
cost,  supposing  potatoes  to  sell  as  low  as  33§  cents  a 
bushel.  One  hundred  and  twent>'-five  bushels  per  acre 
grown  at  a  cost  of  $15  per  acre  and  sold  at  33f  cents  a 


Cost  of  Grotving  Potatoes 


291 


bushel  yield  a  net  profit  of  $20.66  per  acre.  Two  hun- 
dred and  seventy-five  bushels  ])er  acre  grown  at  a  cost  of 
$00  per  acre  and  sold  at  33 1  cents  per  bushel  yield  a 
net  profit  of  $31.66  per  acre.  The  second  profit  is  $5 
more  per  acre  than  the  first. 

"A  farmer  in  Van  Buren  County,  Michigan,  states 
that  his  potato  crop,  mostly  marketed  in  the  fall,  sold  at 
an  average  price  of  44  cents  a  bushel  for  a  period  of  ten 
years.  At  the  latter  price  the  more  expensive  method  of 
culture  would  yield  a  profit  of  $61  per  acre,  against 
$40  from  the  cheaper  method.  Furthermore,  some  of 
the  leading  potato  dealers  of  the  North  have  stated  em- 
phatically that  a  better  quality  of  potatoes  is  normally 
obtained  with  large  yields  than  with  small." 

Place  —  Maine  and  Wisconsin.  Dodge  says  the  Wis- 
consin figures  will  represent  the  expense  put  into  grow- 
ing the  crop  in  most  localities  where  potato  growing  is 
carried  on,  on  a  less  expensive  and  thoroughgoing  basis. 

Authority  —  Dodge,  L.  G.,  Farmers'  Bui.  465. 


Cost  op  Supplies  and  Labor  with 
Rent  of  Land 

Maine 

Wisconsin 

Plowing 

Harrowing 

Fertilizer 

Seed 

Cutting 

Planting 

Cultivating 

Spraj'ing 

Digging 

Rent  of  land 

Total 

$1.50 

.50 

24.00 

5.00 

.75 

.75 

3.50 

3.00 

6.00 

15.00 

$60.00 

$1.25 
.25 

2.50 
.60 
.60 

1.90 
.80  > 

2.10 

5.00 
$15.00 

For  beetles  only. 


292  The  Potato 

Place  —  INIaine. 

Authority  —  Bulletin  of  the  Maine  Department  of 
Agriculture,  March,  1914. 

Average  cost  of  one  acre  of  potatoes  from  records  of 
ten  potato  growers  in  different  localities  in  the  state  :  — 

Cost  of  plowing $2.85 

Harrowing  four  times 4.00 

Fertilizer 36.00 

Applying 2.00 

Seed,  13  bushels  at  80  cents 10.40 

Cutting  seed 1.75 

Planting 4.00 

Cultivating  four  times 4.00 

Hoeing  three  times 3.00 

Spraying  five  times  at  $1.15 5.75 

Harvest 14.00 

$87.75 

Place  —  Maine. 

Authority' — Cleveland,  E.  L.,  Aroostook  County, 
Maine. 

Commercial  fertiUzer  1500  to  2000  pounds      .  $28.50  to  $35 

Preparing  ground  for  seed 3.00 

Seed,  600  pounds 7.00 

Planting 2.50 

Cultivation 3.50 

Gathering  or  harvesting 7.50 

Preparing  for  market .50 

Wear  and  tear  on  implements .50 

Rent  of  land  (tenant  farmer  pays)     ....  10.00  to  20 

Bordeaux  mixture       4.00 

Paris  green .50 

Hauling  to  market 3.50 

Average  yield  of  product  per  acre      ....  220  bushels 

Average  value  of  product  per  acre     ....  $88.00 

Average  size  of  fields       15  acres 

Average  value  per  acre  of  land  growing  such 

crops $75.00  to  $100 

Profit  per  acre 17.00 


Cost  of  Growing  Potatoes  293 

"Much  depends  on  the  weather  conditions  as  to  the 
cost  of  applying  bordeaux  mixture,  paris  green,  cost  of 
cultivation,  labor  and  general  net  results. 

"The  above  estimates  may  be  regarded  the  average 
for  a  series  of  years." 

Place  —  Maine. 

Authority  —  Hurd,  Prof.  W.  D.,  formerly  dean  of  the 
College  of  Agriculture,  University  of  Maine. 

From  records  for  several  years  on  the  college  farm  at 
Orono,  the  cost  of  growing  a  ten-acre  field  of  potatoes  is 
about  as  follows :  man  and  team  labor  are  reckoned  at 
$3.50  per  day,  extra  men  at  $1.50  per  day. 


Plowing  at  $2  per  acre $20.00 

HarroAS-ing  five  times,  $3.50  per  acre 17.50 

Fertilizer  (home  mixture)  $30  a  ton 225.00 

Seed,  130  bushels,  75  cents  a  bushel 97.50 

Disinfecting  seed  (labor  and  material) 3.00 

Cutting  seed  (by  hand)  at  6  cents  per  bushel      .     .     .  7.80 

Planting,  team  and  two  men  three  days,  $5    .     .     .     .  15.00 

Harrowing  or  weeding  before  crop  is  up,  four  times      .  10.50 

Cultivating  crop  eight  times  at  $3.50 28.00 

Spraying  six  times  ($1  per  acre  each  application)     .     .  60.00 

Hand  hoeing  and  pulling  weeds  once  (if  necessary)  .  15.00 
Digging  and  hauling  to  storehouse  or  station  at  $15 

per  acre 150.00 

Rent  of  land  (5  per  cent  on  $50  per  acre  value),  10 

acres , 25.00 

Depreciation  of  implements  (plows,  harrows,  planter, 

sprayer,  digger,  etc.),  value  $250  estimated  at  10  per 

cent 25.00 

$699.30 


Value  of  crop,  225  bushels  to  acre  (2250  bushels  at  50 

cents) $125.00 

Value  per  acre 112.50 

Cost  of  growing  per  acre 69.93 

Net  profit  per  acre 42.57 


294 


The  Potato 


Place  —  New  York. 

Authority  —  Results  of  a  survey  by  the  Department 
of  Farm  Management,  New  York  State  College  of  Agri- 
culture. 

Cost  of  Growing  Potatoes 


1913 

1914 

Number  of  farms 

Number  of  acres 

Average  acres  per  farm     .     .     . 
Average  yield  per  acre      .     .     . 

18.0 
185.4 

10.3 
102.7 

21.0 

158.8 

7.6 

154.7 

Cost  of  Growing  per  Acre 

Amount 

Amount 

Seed 

10  bu. 

$7.67 

12.6  bu. 

$8.03 

Fertilizer   .     .     . 

412  lb. 

5.17 

431  lb. 

5.72 

Manure      .     .     . 

6.14 

2.06  tons 

4.64 

Spray  materials 

.83 

.80 

Man  labor      .     . 

77.7  hr. 

13.30 

81.2  hr. 

15.57 

Horse  labor    .     . 

77.4  hr. 

10.66 

72.4  hr. 

12.41 

Equipment     .     . 

3.58 

3.71 

Use  of  land  at  6  per  cent 

4.53 

5.18 

Use  of  buildings  at  8  per 

cent 

1.27 

1.09 

Interest  at  5  per  cent  . 

.88 

All  other  costs     .     .     . 

.63 

.04 

Total  cost    .     .     . 

$53.74 

$58.07 

Cost    of    marketing    pei 

bushel 

.12 

.05 

Cost  of  growing  per  bushe 

.52 

.38 

Cost  of  gromng  and  mar- 

keting per  bushel 

.63 

.43 

Profit  per  acre     .     .     . 

7.38 

-16.03 

Profit  per  bushel      .     . 

.07 

-     .10 

Profit  per  man,  hour    . 

.08 

-     .18 

Cost  of  Ci wiring  Potatoes 


295 


:JLJ  Ijb 


Apr.  May  June  July  Aug.  Sept.  Oct. 


Apr.  May  June  July  Aug.  Sept.  Oct. 


Fig.  28. 


(see  page  298) 


Fig.  29. 


Place  —  California. 

Authority  —  Shaiiklin,  L.  F.,  Lompoc,  California. 
Quoted  from  Grubb  and  Guilford,  "The  Potato." 

L.  F.  Shanklin  of  Lompoc,  California,  estimates  the 
cost  of  producing  an  acre  of  potatoes  as  follows :  — 

Use  of  land  (wiU  rent  for) 130.00 

Seed,  400  pounds  at  1|  cents 6.00 

Plowing  and  preparation        5.00 

Cultivation  twice  —  hoeing  once 1.00 

Digging  and  picking 3.00 

Sacks  5  cents,  sacking  5  cents  (100  sacks) 10.00 

Hauling 1.00 

$56.00 
His  average  crop  is  :  — 

70  sacks  first,  115  pounds  to  sack,  at  $1.30  per  100  .  .  $80.00 
30  sacks  seconds,  120  pounds  to  sack,  at  $1.00  per  100  .  .  36.00 
30  sacks  cow  feed  or  waste  at  10  cents  per  100      .     .     .         3.00 

$119.50 

Place  —  New  York. 

Authority  —  Department  of  Farm  Management,  New 
York  State  College  of  Agriculture. 


Cost  of  Growing  Potatoes 
IN  New  York 

Steuben  Co. 

Clinton  &  Franklin 
Cos. 

No.  farms        

Yield  per  acre      .... 
Acres  per  farm    .... 

355.0 

131.0 

14.7 

300.0 
179.0 

7.2 

296 


The  Potato 


Cost  op  Growing 


Amount 


Amount 


Seed 

Fertilizer 

Manure 

Spray  materials        .     .     . 

Man  labor 

Horse  labor 

Use  of  equipment    .     .     . 

Land 

Buildings 

All  other  costs  .... 
Total  cost  of  growing  per 

acre 

Total  cost  of  growing  per 

bushel 

Cost  of  marketing  per  acre 
Cost    of    marketing     per 

bushel 

Profit  per  acre  .... 
Profit  per  bushel  .  .  . 
Profit  per  man,  hour    .     . 


10.2  bu. 
120.0  lbs. 
2.3  tons 


66.0  hrs. 
68.9  hrs. 


$9.48 

1.66 

4.61 

.20 

11.55 

10.33 

3.45 

3.00 

.81 

.45 

45.54 

.35 


.054 
2.22 
.02 
.03 


12  bu. 
407  lbs. 
3.4  tons 

110.4  hrs. 
88.6  hrs. 


$6.79 

5.77 

7.21 

.22 

17.65 

10.20 

3.94 

7.00 

1.56 

.12 

60.68 

.33 
6.32 

.044 
36.72 
.21 
.33 


Place  —  Utah. 

Authority  —  Harper,  W.  F.,  Smithfield,  Utah.     Quoted 
in  Grubb  and  Guilford,  "The  Potato." 

Plowing,  harrowing  and  leveling  the  land $5.00 

Fifteen  loads  of  manure  at  25  cents  per  load    ....  3.75 

Hauling  manure  at  75  cents  per  load       11.25 

Seed       10.00 

Cutting  and  planting  seed 9.00 

Cultivating,  weeding  and  irrigating 5.00 

Picking  and  sacking 10.00 

Loading  on  car 4.50 

$59.00 

Results  of  a  survey  in  New  York  state 

In    the    agricultural    survey    of    Tompkins    County, 
Warren,  Livermore,  and  others:  "The  potato  crop  ranks 


Cost  of  Growing  Potatoes  297 

third  in  value  of  crops,  but  the  acreage  per  farm  is  very 
small,  averaging  1.7  acres.  Of  982  farms  in  four  town- 
ships, only  33  grew  more  than  5  acres  of  potatoes  and  only 
2  grew  over  10  acres.  Nearly  all  of  the  crop  is  grown  in 
this  small  way,  but  the  crop  is  usually  a  profitable  one. 

"Apparently  the  larger  acreages  are  profitable.  The 
average  labor  income  of  farmers  growing  more  than  5 
acres  of  potatoes  is  $853. 

"Of  605  farms  operated  by  owners,  11  sold  over  $500 
worth  of  potatoes.  These  men  made  good  profits.  The 
lowest  labor  income  was  $724,  and  the  highest  $2146; 
the  average  was  $1511.  The  farms  averaged  141  acres. 
An  average  of  6.3  acres  of  potatoes  were  grown  per  farm, 
with  an  average  yield  of  219  bushels  per  acre.  The 
average  receipts  from  the  sale  of  potatoes  were  $732, 
which  constituted  24  per  cent  of  the  total  sales. 

"Of  nine  of  these  farms  the  most  important  sale  was 
milk,  with  potatoes  second.  Each  of  the  farms  received 
some  income  from  hay,  grain,  eggs,  or  lambs,  etc. 
The  average  labor  income  on  these  farms  was  $1575. 

"One  farm  of  134  acres  was  a  potato,  hay  and  grain 
farm,  with  some  sales  of  eggs,  milk,  etc.  This  farm  gave 
a  labor  income  of  $1649. 

"One  farm  of  71  acres  sold  potatoes,  lambs,  hay,  grain, 
eggs,  etc.,  and  made  a  labor  income  of  $794.  On  many 
farms  that  have  soils  adapted  to  potatoes,  it  would  seem 
desirable  to  increase  the  area  of  this  crop.  When  the 
crop  can  be  increased  to  ten  acres  per  farm,  it  will  justify 
the  purchase  of  a  planter,  sprayer  and  digger.  Only 
by  growing  a  much  larger  acreage  per  farm  can  one  afford 
this  labor-saving  machinery  that  will  go  far  toward 
making  the  crop  pay.  It  will  also  pay  to  try  much 
heavier  applications  of  fertilizer." 


298  The  Potato 

Other  survey  results 

In  a  survey  of  the  incomes  of  178  New  York  farms, 
Burritt  ^  obtained  some  interesting  figures  which  show 
comparisons  of  certain  kinds  of  farms.  Unfortunately 
the  number  of  potato  farms  in  the  survey  was  very  small 
and  may  not  mean  very  much,  but  the  tables  give  a 
suggestive  comparison.  He  says :  "  All  farms  were  di- 
vided into  two  classes.  Mixed  or  general  farms  are  those 
on  which  no  one  source  of  income  constitutes  40  per  cent 
of  the  total  income.  Special  farms  are  those  deriving 
40  per  cent  or  more  of  their  income  from  one  special 
crop  or  industry.  This  latter  class  was  further  divided 
into  dairy,  fruit,  potato  and  truck  farms." 

The  seasonal  distribution  of  man  and  horse  labor  is 
one  of  the  factors  which  determine  the  feasibility  of 
growing  potatoes  along  with  other  crops,  and  represents 
no  small  measure  of  profitableness  when  considered  in 
the  whole  farm  scheme.  The  figures  28  and  29  (page  295) 
are  used  by  Warren  to  represent  the  distribution  of 
horse  and  man  labor  respectively,  on  1 1  acres  of  potatoes. 
Black  is  work  fixed  as  to  time,  white  is  plowing  and 
marketing. 

1  Bui.  271,  Agri.  Expt.  Sta.,  Cornell  University. 


Cost  of  Growing  Potatoes 


299 


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Cost  of  Growing  Potatoes 


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No.  of  farms      .     .     . 
Average  area      .     .     . 
Total  capital      .     .     . 
Real  estate    .... 
Machinery  and  tools 

Horses 

Other  live  stock     .     . 
Seed  and  feed    .     .     . 
Miscellaneous    .     .     . 

302 


The  Potato 


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No.  of  farms  .  .  . 
Total  paid  labor  .  . 
Unpaid  family  labor  . 
Board  of  laborers  .  . 
Total     labor     except 

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Farmer's   estimate   of 

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Cost  uf  Growing  Potatoes 


303 


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No.  of  farms      .     .     . 
Total  expense    .     .     . 

Labor       

Seed  and  feed    .     .     . 
Fertilizers      .... 
Machinery  and  repairs 
Building  and  fences    . 
Live  stock     .... 
Miscellaneous    .     .     . 

304 


The  Potato 


Place  —  New  York  (St.  Lawrence  County). 

Authority  —  Circular  of  Information  of  the  New  York 
State  School  of  Agriculture  at  St.  Lawrence  University, 
April,  191L 

The  detailed  cost  of  growing  an  acre  of  early  potatoes 
for  the  years  1909  and  1910  was  as  follows :  — 

Early  Potatoes 


Cost  per  Acbb 


1909 


1910 


Yield  (large),  192.22  bushels  at  62  cents 
Yield  (small),  26.65  bushels  at  20  cents 
Yield  (large),  122.15  bushels  at  $.477  . 
Yield  (small),  22|  bushels  at  20  cents  . 

Plowing 

Harrowing       

Planting 

Cultivating 

Hoeing 

Spraying 

Digging  and  delivering 

Fertilizer,  2000  pounds 

Fertilizer,  1899  pounds 

Seed,  18i  bushels  at  SI.  18 

Seed,  17i  bushels  at  S  .40 

Paris  green 

Total  cost  per  acre 

Profit  per  acre        

Loss  per  acre , 


$119.18 
5.33 


$95.29 
29.22 


$58.27 
4.50 


4.00 

2.01 

4.39 

2.25 

4.42 

4.29 

1.93 

3.01 

1.81 

.87 

8.49 

9.39 

18.19 

14.61 

28.00 

25.72 

21.66 

6.90 

2.40 

2.92 

$71.97 
9.21 


"The  soil  upon  which  the  main  crop  of  late  potatoes 
was  grown  is  a  sandy  loam.  The  field  had  no  clover 
sod,  indeed,  no  sod  of  any  sort  except  the  quack-grass  and 
weeds.  A  higher  cost  for  chemicals  was  necessary  to 
make  good  this  deficiency.  Three  and  one-third  acres 
of  the  field  contained  quack-grass  and  foul  seeds.     This 


Cost  of  Groiving  Potatoes  305 

land  was  plowed  twice  in  the  spring  with  frequent  culti- 
vation, which  very  nearly  destroys  every  trace  of  quack- 
grass.  The  low  cost  of  hand  labor  on  the  field  warrants 
the  statement  that  weed  growth  was  practically  de- 
stroyed by  cultivation  before  the  potatoes  were  planted, 
and  by  the  weeder  after  they  were  planted.  It  is  impor- 
tant that  we  impress  upon  the  users  of  weeders  and  smooth- 
ing harrows  the  absolute  necessity  of  beginning  opera- 
tion at  once  after  the  potatoes  or  seeds  have  been  planted. 
If  the  weeds  become  rooted,  even  though  they  may  not 
show  very  much  above  ground,  the  light-fingered  tools, 
which  are  only  safe  to  use  on  the  growing  plants,  will 
have  very  little  eft'ect  upon  them.  Farmers  are  often 
disappointed  in  the  effect  of  weeders,  simply  because  the 
weeder  has  given  the  weed  the  same  encouragement  which 
it  gives  to  the  plant  under  cultivation. 

"The  seed  potatoes  which  were  kept  in  an  outdoor  pit 
during  the  winter  were  taken  from  the  pit  April  18th, 
spread  thinly  on  the  barn  floor  and  stirred  occasionally  to 
prevent  long  sprouts  from  growing.  They  were  planted 
at  varying  dates  from  May  28th  to  June  10th.  None 
of  the  sprouts  were  broken  in  handling  or  planting.  The 
pieces  were  cut  as  nearly  cubical  as  possible,  and  weighed 
about  2  oz.  each.  The  number  of  eyes  varied  from  1  to 
5,  the  seed  ends  often  containing  5  to  6  eyes.  No  eft'ort 
was  made  to  reduce  the  size  of  the  seed  piece  from  the 
seed  end  of  the  potato,  in  fact  it  is  a  fatal  error  to  do  so. 
Only  one  or  two  stalks  will  develop.  The  pieces  were 
dropped  14^  inches  by  36  inches." 

"The  cost  by  items  does  not  show  marked  difference 
for  the  two  years,  with  the  exception  of  digging  and 
delivering.  A  part  of  this  saving  was  due  to  a  lighter 
yield  and  a  part  to  more  economical  methods  of  handling." 


306  The  Potato 

Four  and  One-third  Acres  Potatoes  (1910) 


Yield,  9581  bushels  (large)  at  40  cents 
Yield,  53  bushels  (small)  at  20  cents  . 

Plowing 

Harrowing 

Planting 

Cultivating 

Hoeing,  hand  labor        

Spraying,  1050  gallons  per  acre  .     .     . 

Digging  and  delivering 

732  bushels  seed  at  40  cents        .     .     . 

8234  pounds  fertiUzer 

42  pounds  paris  green 

Profit,  S75.87 


$15.33 
9.75 
18.63 
13.02 
3.81 
40.70 
63.32 
29.40 

111.57 
12.60 


$383.40 
10.60 


$318.13       $394.00 


Potatoes 


Cost  per  Acre 


1909 


1910 


Yield  (large),  289|  bushels  at  40  cents 
Yield  (small),  27  bushels  at  20  cents  . 
Yield  (large),  221J  bushels  at  40  cents 
Yield  (small),  12.2  bushels  at  20  cents 

Plowing 

Harrowing 

Planting 

Cultivating 

Hoeing  (hand  labor) 

Spraying,  1000  gallons 

Spraying,  1050+  gallons 

Digging  and  delivering 

Seed,  16  bushels  at  73  cents  .  .  .  . 
Seed,  17  bushels  at  40  cents  .     .     .     . 

Fertilizer,  1800  pounds 

Fertilizer,  1900+  pounds 

Paris  green,  7  pounds 

Paris  green,  9.6+  pounds 

Total  cost  per  acre 

Profit  per  acre        


$115.92 
5.40 


4.18 
1.90 
4.30 
1.73 

.68 
8.49 

24.01 
11.68 

25.20 

2.10 


$84.27 
37.05 


$88.48 
2.44 


3.54 
2.25 
4.30 
3.00 

.88 

9.39 
14.61 

6.80 

25.75 

2.91 


$73.43 
17.49 


Cost  of  Growing  Potatoes  307 

Place  —  Minnesota. 

Authority  —  Bulletin  48,  Bureau  of  Statistics,  by  Hays 
and  Parker. 

The  cost  of  producing  potatoes,  under  garden  condi- 
tions, is  given  on  pages  308  and  309. 

Cost  of  hauling 

Potatoes  are  a  bulky  crop  and  the  cost  of  hauling  is 
no  inconsiderable  item.  Andrews  ^  says  :  "  In  many  ways 
they  are  hauled  under  conditions  similar  to  those  under 
which  grain  is  hauled,  and  the  average  cost  per  100  pounds 
for  hauling  potatoes  from  farms  to  shipping  pomts  is  the 
same  as  for  wheat  and  2  cents  more  than  for  oats,  corn 
or  barley. 

"The  averages  for  the  United  States  are  affected  more 
by  the  figures  for  the  north  Atlantic  and  north  central 
states  than  by  the  other  states  and  the  territories,  since 
about  three-fourths  of  the  potato  crop  of  the  United 
States  is  produced  east  of  the  Rocky  ]\Iountains  and 
north  of  the  Potomac  and  Ohio  rivers  and  southern 
boundaries  of  Missouri  and  Kansas. 

"The  average  cost  of  hauling  from  farms  to  shipping 
points  in  this  region  is  9  cents  per  100  pounds,  or  5.4 
cents  per  bushel.  The  lowest  average  cost  is  for  three 
counties  in  Rhode  Island,  where  an  average  of  three  trips 
per  day  is  made  to  and  from  shipping  points,  and  the 
highest  average  cost  in  the  north  Atlantic  and  north 
central  states  is  in  South  Dakota,  where  the  average 
time  of  round  trip  between  farm  and  shipping  point  is 
longer  than  one  working  day." 

'  Andrews.  Cost  of  Hauling  Crops  from  Farms  to  Shipping  Points. 
U.  S.  D.  A.,  Bureau  of  Statistics,  Bui.  49. 


308 


The  Potato 


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310 


The  Potato 


Table  XXXI. 


-Average  Cost  op  Hauling  Potatoes  from 
Farms  to  Shipping  Points 


Il 

o 

Average 

State  or  Territory 

Miles 
to  Ship- 
Point 

Days 

for 
Round 
Trip 

Pounds 
in  One 
Load 

Cost 
per 
Load 

Cost 
per  100 
Pounds 

Maine 

9 

7.6 

0.7 

2393 

$2.58 

$0.11 

New  Hampshire      .     . 

5 

6.6 

.6 

2330 

2.21 

.09 

Vermont 

7 

7.1 

.6 

2321 

1.93 

.08 

Massachusetts    .     .     . 

3 

10.6 

.6 

2300 

2.40 

.10 

Rhode  Island      .     .     . 

3 

5.0 

.3 

1933 

.98 

.05 

Connecticut  .... 

2 

6.7 

.7 

2500 

2.80 

.11 

New  York      .... 

34 

7.1 

.7 

2896 

2.49 

.09 

New  Jersey    .... 

9 

4.8 

.6 

2583 

2.08 

.08 

Pennsylvania      .     .     . 

22 

6.6 

•7 

2809 

2.61 

.09 

Delaware 

1 

10.6 

.7 

1500 

2.80 

.19 

Maryland 

7 

5.7 

.5 

2536 

1.62 

.06 

Virginia 

22 

9.1 

.8 

1880 

2.30 

.12 

West  Virginia     .     .     . 

17 

12.2 

1.2 

1965 

4.21 

.21 

North  Carolina  .     .     . 

27 

11.4 

1.1 

1437 

2.92 

.20 

South  Carolina  .     .     . 

3 

9.9 

.7 

1267 

2.01 

.16 

Georgia 

16 

11.0 

1.0 

1466 

2.52 

.17 

Florida 

9 

7.7 

.6 

1544 

2.05 

.13 

Ohio 

22 

7.2 

.7 

2748 

2.39 

.09 

Indiana 

12 

6.4 

.6 

3075 

1.72 

.06 

Illinois 

13 

6.0 

.6 

2700 

1.94 

.07 

Michigan 

47 

8.0 

.7 

2766 

2.25 

.08 

Wisconsin       .     .     .     . 

28 

9.5 

.8 

2595 

2.46 

.09 

Minnesota     .     .     .     . 

20 

9.7 

.8 

3890 

2.68 

.09 

Iowa 

14 

5.9 

.5 

2293 

1.48 

.06 

Missouri 

13 

9.4 

.8 

2035 

2.05 

.10 

South  Dakota    .     .     . 

4 

15.5 

1.1 

2950 

3.51 

.12 

Nebraska       .     .     .     . 

14 

11.1 

.8 

2732 

2.64 

.10 

Kansas      .     .     .     .     . 

6 

5.2 

.6 

2658 

1.82 

.07 

Cost  of  Growing  Potatoes 


311 


^   W   Q 
gig 

III 
o 

Average 

State  ob  Teeritory 

Miles 
to  Ship- 
ping 
point 

Days 

for 

Round 

Trip 

Pounds 
in  One 
Load 

Cost 
Lo"d 

Cost 
per  100 
Pounds 

Kentucky       .     . 
Tennessee       .     . 

19 
19 

8 
11 

6 
26 

3 
11 

12.4 
10.0 
14.0 
11.9 
12.6 
12.4 
7.9 
13.6 

1.4 
.8 
1.2 
1.1 
1.3 
1.1 
.6 
1.3 

1834 

1874 
1450 
1336 
1400 
1460 
1867 
1523 

4.44 
1.99 
3.14 
2.85 
4.00 
2.86 
1.65 
3.04 

.24 
.11 

.22 

Mississippi     .     . 
Louisiana       .     . 
Texas    .... 

.21 
.29 
.20 

Indian  Territory 
Arkansas   .     .     . 

.09 
.20 

Montana  ... 
Wyoming       .     . 

9 
5 

20 
3 
5 
4 

15 
9 
7 

14.0 
25.5 
12.2 
22.7 
10.1 
15.5 
7.8 
9.7 
12.0 

1.2 
2.3 
1.1 
2.1 

.7 

1.4 

.8 

.9 

1.1 

2811 
2860 
3100 
1800 
3300 
3125 
2617 
4028 
4914 

5.47 
9.20 
4.71 
9.09 
2.31 
5.17 
3.38 
3.15 
4.72 

.19 
.32 
.15 

New  Mexico  .     . 

Utah     .... 

.50 
.07 

Idaho    .... 

.17 

Washington   .     . 

.13 

.08 

California       .     . 

I : 

.10 

Geographic  divisior 
North  Atlantic 
South  Atlantic 
North  Central 
South  Central 
Western      .     . 

94 
102 
193 
103 

77 

7.0 
9.6 
8.1 
12.1 
11.3 

.7 

.9 

.7 

1.2 

1.0 

2717 
1871 
2651 
1660 
3615 

2.55 
2.74 
2.30 
3.30 
4.05 

.09 
.15 
.09 
.20 
.11 

States  and  Territo 
represented     . 

ries 

569 

8.2 

.7 

2679 

2.34 

.09 

312 


The  Potato 


Table   XXXII.      Cost   of   Hauling   Potatoes   prom   Most 
Remote  Farms  to  Shipping  Points,  as  Reported 


State  or  Territory 


Shipping 
Point 


Maine     .     .     . 
New  Hampshire 
Vermont     .     . 
Massachusetts 
Rhode  Island  . 
Connecticut     . 
New  York  .     . 
New  Jersey 
Pennsylvania  . 
Delaware    .     . 
Maryland  .     . 
Virginia       .     . 
West  Virginia 
North  Carolina 
South  Carolina 
Georgia  .     .     . 
Florida  .     .     . 
Ohio       .     .     . 
Indiana       .     . 
Illinois  .     .     . 
Michigan    .     . 
Wisconsin  .     . 
Minnesota  .     . 
Iowa       .     .     . 
Missouri 
South  Dakota 
Nebraska    .     . 
Kansas  .     .     . 
Kentucky  .     . 


Alabama     .     . 
Mississippi 
Louisiana    .     . 
Texas     .     .     . 
Indian  Territory 


16.0 
13.0 
15.0 
19.0 
10.0 
15.0 
25.0 
15.0 
16.0 
15.0 
12.0 
46.0 
40.0 
50.0 
15.0 
30.0 
24.0 
30.0 
15.0 
24.0 
30.0 
30.0 
30.0 
13.0 
20.0 
30.0 
37.5 
9.5 
37.5 
35.0 
37.5 
30.0 
25.0 
46.0 
15.0 


Round 
Trip 


1.0 
1.0 
1.0 
1.0 

.5 
1.0 
3.0 
1.5 
1.0 
1.0 
1.0 
5.0 
4.0 
4.0 
1.5 
2.5 
2.0 
2.0 
2.0 
1.5 
2.0 
2.0 
2.0 
1.0 
2.0 
3.0 
3.0 
1.0 
5.0 
3.0 
4.0 
2.5 
3.0 
4.0 

.5 


Pounds 
IN  One 
Load 


1600 
2000 
3000 
3500 
1500 
2000 
3000 
3500 
3500 
1500 
4000 
3000 
3500 
1600 
1600 
2000 
1500 
2000 
3250 
3500 
3500 
2500 
3000 
2000 
1500 
3000 
4000 
3000 
ISOO 
1500 
1200 
1500 
900 
3000 
2000 


Cost  per 
Load 


$3.50 
4.00 
3.50 
4.75 
1.50 
4.00 

12.00 
5.62 
4.00 
4.00 
5.00 

20.00 
8.00 

11.00 
3.75 
5.00 
5.00 
8.00 
6.00 
6.00 
6.00 
6.00 
7.00 
3.00 
3.00 
7.50 
9.00 
2.50 

15.00 
8.25 

10.00 
6.88 

12.00 
7.52 

13.75 


Cost  per 

100 

Pounds 


Cost  of  Groiving  Potatoes 


313 


Miles  to 

Days  for 

Pounds 

Cost  per 
Load 

Cost  per 

State  or  Territort 

Shipping 

Round 

IN  One 

100 

Point 

Trip 

Load 

Pounds 

Arkansas    

40.0 

2.5 

2250 

7.50 

.33 

Montana    . 

30.0 

3.0 

3500 

13.50 

.39 

Wyoming  . 

55.0 

6.5 

4500 

22.75 

.51 

Colorado     . 

70.0 

7.0 

2500 

33.00 

1.40 

New  Mexico 

57.5 

4.0 

2000 

22.00 

1.10 

Utah  .    .     . 

25.5 

2.5 

3000 

8.75 

.29 

Idaho      .     . 

25.0 

3.0 

2500 

10.50 

.42 

Washington 

30.0 

3.0 

800 

12.00 

1.50 

Oregon    .    . 

35.0 

3.0 

2000 

13.50 

.68 

CaUfornia   . 

32.0 

3.0 

4000 

12.75 

.32 

INDEX 


Africa,  production  of  potatoes  in,  3. 

alcohol,  manufacture  of,  274. 
slops  or  residue,  282. 
use  for,  271. 

alfalfa  in  rotation,  111,  112. 

alsike  clover  in  rotation,  111. 

Aroostook  County,  Me.,  as  a  potato 
center,  7,  113. 

arsenical  injury,  202. 

Asia,  production  of  potatoes  in,  3. 

association  of  characters  in  breed- 
ing, 75. 

Australia,   production   of   potatoes 
in,  3. 

Austria-Hungary,     production     of 
potatoes  in,  2,  3. 

bacteria  in  soils,  102. 

bacterial  wilt,  200. 

Baker,  21. 

barley,  value  in  United  States,  3. 

world's  crop,  1. 
Bauhin,  15. 
belladonna,  1. 
black-leg,  199. 
blister-beetle,  175. 
bordeaux  mixture,  217. 
botanical  characteristics,  21. 
breeding,  47-85  (chapter  IV). 
bud-selection,  57. 
bud-sports,  57,  76. 

calcium,  124. 

Canada,  production  of  potatoes  in, 
3,  13. 

de  Candolle,  15. 
capsicum,  1. 

Carbondale,  Colo.,  as  a  potato  cen- 
ter, 7. 
Cardan,  15. 


Chester  County,  Pa.,  potatoes  con- 
sumed on  farms,  12. 
Cierca  de  Leon,  14. 
classification,  21. 
climate,  86  (chapter  V). 
Clusius,  15. 

Colorado  potato  beetle,  170. 
composition  of  potatoes,  262. 
constitutional  degeneracy,  205. 
control    measures    against    disease, 

206-225  (chapter  XI). 
corn,  value  in  United  States,  3. 

world's  crop,  1. 
cost  of  growing  potatoes,  287-313 
(chapter  XV). 

harvesting,  234. 

hauling,  307. 
cotton,  value  in  United  States,  3. 
cover-crops,  105. 
critical  period,  89,  95. 
crop  reporter,  257. 
crossing,  method  of,  78. 
cultivation  of  potato,  163. 
culture  of  potato,  89. 
curly  dwarf,  203  ;   control,  206. 
cutting  seed,  156. 
cyanimid  as  fertilizer,  120,  121. 

Dala  potato,  73. 
Darwin,  76. 

description  of  potato,  22. 
desiccated  potatoes,  284. 
digging,  methods  of,  230, 
disease,  97. 

from  organisms  in  soil,  212. 

proof  varieties,  50,  221. 
diseases  of  potato,  183-205  (chapter 

X). 
Dodge,  70. 
drainage,  95. 


315 


316 


Index 


Early  and  late  potatoes,  marketing, 

249. 
early  blight,  189. 
East,  74,  78,  82,  83. 
eastern  shore  of  Va.  and  Md.  as 

potato  centers,  7. 
egg-plant,  1. 
engines,  165. 

England,  introduction  into,  15. 
Europe,  production  of  potatoes  in, 

3. 
European    Russia,    production     of 

potatoes  in,  2. 
expense  of  marketing,  255. 

family  consumption,  statistics,  11. 
farm  manures,  130. 
fertilizer  practices,  115,  126. 
fertilizers,  113  (chapter  VI). 

market  forms,  116. 
Fischer,  75,  76. 
Fitch,  25,  27,  30,  33. 
flea-beetles,  173. 
flour,  potato,  284. 
France,  production  of   potatoes  in, 

2,  3. 
freight  charges,  253. 
Fruwirth,  73,  74. 
Funk,  11. 
fusarium  dry  rot,  196. 

wilt,  195. 

Gerard,  16. 

Germany,    production  of  potatoes 

in,  2,  3. 
yields  to  the  acre,  12. 
grading,  245. 
Great  Britain,  yields  to  the  acre, 

12. 
Greeley,  Colo.,  as  a  potato  center,  7. 
green  manures,  105. 
growing  crop,  care  of,  160  (chapter 

VIII). 

hand  planting,  151. 
harvest,  time  to,  226. 
harvesting  cost,  234. 

labor.  234. 

potatoes,  226-235  (chapter  XII). 


hauling,  cost  of,  307. 
hay-plants,  109. 

value  of  in  United  States,  3. 
heat,  90. 
heated  cars,  253. 
henbane,  1. 
Herbal,  16. 
Heriot,  47. 

hill  and  drill  planting,  146. 
\i\\  selection,  54. 

history  of  potato,  14  (chapter  II). 
human  food,  uses  as,  260. 
Humboldt,  15. 

hybridization,     improvement     by, 
77-84. 

ideals  of  the  potato  crop,  48,  49. 
improvement,  methods  of,  56. 
individual  selection,  62. 
insects,  170-182  (chapter  IX). 
Ireland,  introduction  into,  16. 
Irish  famine,  20. 

Kaw  Valley,  as  a  potato  center,  7. 
Kohler,  31,  33. 

late  blight,  190 ;   treatment,  214. 
leaf-hoppers,  129. 
leaf  roll,  204  ;  control,  206. 
Livingston  County,  N.  Y.,  potatoes 

consumed  on  farms,  11. 
local    dealers,    marketing   through, 

243. 

McCormick    variety,    resistant    to 
heat,  91. 

Macoun,  12. 

Maine,  production  of  potatoes  in, 
3. 

manures  and  fertilizers,  113  (chap- 
ter VI). 

marketing    through    local    dealers, 
243. 

markets,  249. 

and   marketing,   237-258    (chap- 
ter XIII). 

mass-selection,  61. 

Michigan,   production   of   potatoes 
in,  3. 


Inde.} 


317 


Milward,  33. 

Minnesota,  production  of  potatoes 

in,  3. 
mosaic,  control,  206. 
Myers,  59. 

net  necrosis,  203. 
Newman,  73. 

New  York,  production  of  potatoes 
in,  3. 
State    Potato  Ass'n,   score    card 
of,  53. 
nitrate  of  lime,  120. 
nitrogen,  119. 

Norfolk,  Va.,  as  a  potato  center,  7. 
North  America,  introduction  into, 
15. 
production  of  potatoes  in,  3. 

oats,  value  in  United  States,  3. 

world's  crop,  1. 
Orton,  73. 

packages,  245. 

papas,  16. 

Paradisus,  16. 

Parkinson,  16. 

Parmentier,  18. 

pedigree  breeding,  62. 

Penn.,  production  of  potatoes  in,  3. 

Peru,  original  home  of  potato,  14. 

Phipps,  20. 

phosphorus,  122. 

picking  and  sorting,  232. 

plant  food,  94,  114. 

planting,  133-142  (chapter  VII). 

hill  and  drill,  146. 

tools,  148. 
potassium,  123. 
potato  flour,  284. 

plant  louse,  177. 

pomace,  283. 

stalk  wec\'il,  179. 

wart,  198. 
"Potatoes  of  Virginia,"  18. 

value  in  United  States,  3. 
poultry  food,  283. 
powdery  scab,  201. 
power  for  potato  fields,  165. 


price  of  potato  land,  88. 

prices,  250. 

production  on  farms,  statistics,  7. 

world,  2. 

in  difTerent  countries,  2. 
pure  lines,  58. 

quality  when  cooked,  261. 

Raleigh,  Sir  Walter,  15. 

red  clover  in  rotation,  111. 

Red    River    Valley,    as    a    potato 

center,  7. 
rhizoctoniose,  194. 
rice,  world's  crop,  1. 
Rose,  14. 

rotation,  86  (chapter  V). 
running  out  of  varieties,  72. 
Russia,  production  of  potatoes  in, 


Sacramento,    Cal.,     as     a     potato 

center,  7. 
Salaman,  78,  82,  83,  84. 
San    Joaquin,    Cal.,  as    a    potato 

center,  7. 
scab,  common,  199. 

powdery,  201. 
score-card,  152. 
seed,  cutting,  156. 

potatoes,  152. 

treatment  for  scab,  153,  208. 

selection,  55,  57. 
shipping,  246. 
silver  scurf,  196. 
soils,  86  (chapter  V). 
soil  texture,  93. 
Solanum  Cardiophyllum,  21. 

Commersonii,  21. 

Jaracsii,  21. 

Maglia,  21. 

oxycarpum,  21. 

tuberosum,  21. 
sorting,  232. 
South      America,     production      of 

potatoes  in,  3. 
Spain,  introduction  into,   15. 
Spillman,  12,  70. 
spindling  sprout,  203. 


318 


Index 


stalk  borer,  180. 

starch  manufacture,  265. 

use  for,  265,  270. 
stock  food,  use  as,  280. 
storage,  258. 
Stuart,  27,  33,  43,  45. 
sulphur,  126. 
survey  results,  growing  costs,  296. 

texture  of  cooked  potatoes,  263. 
three-lined  leaf-beetle,  176. 
tillage,  results  of,  137. 

tools,  135. 
tip-burn,  168,  202. 
tobacco,  1. 

value  in  United  States,  3. 
tomato,  1. 
tools,  tillage,  35. 
tortoise  beetles,  176. 
tractors,  165. 

tuber-unit,  method  of  breeding,  62. 
types  of  potato  growing,  97. 

United    Kingdom,    production    of 

potatoes  in,  2. 
United      States,      production      of 

potatoes  in,  2,  3. 
yields  to  the  acre,  12. 


Uses  of   potato,  259-286    (chapter 
XIV). 

varieties  of  Iowa  and  central  west, 

25. 
verticillium  wilt,  196. 

Waid's  experiments,  72. 
Warren,  11. 

water  requirements,  92. 
Webber,  62. 
weed  killing,  140. 

wheat    value     in     United     States, 
3. 
world's  crop,  1. 
white  grubs,  180. 
wild  potatoes,  47. 
Wilson,  81. 
wire  worms,  181. 

Wisconsin,  production  of  potatoes 
in,  3. 

yield,  highest   recorded   in  United 

States,  12. 
yields,  12,  87. 

Zavitz,  71. 


PItOnRTr  UBRARY 
N.  C  State  CoUene 


United  States  of  America. 


T 


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